I. Anatomical contributions to plant taxonomy I

The affinities of Hua Pierre and Afrostyrax Perkins et Gilg

P. Baas

Rijksherbarium, Leiden

Contents

Summary 161

Introduction 161

Techniques I <>3

Materials 163

Synopsis of the family Huaceae 163

Results and Discussion 164

Taxonomical and macromorphological notes 164 and seed 165 Ovary, fruit anatomy Pollen morphology t66

167 Vegetative anatomy

Hua 167

Afrostyrax 172 The Halphen reaction 179

Discussion of some of the characters of Huaceae 179

of the 182 Hua and Afrostyrax as related genera family Huaceae with other 183 Huaceae compared plant groups Perkins' and Chevalier's view: Styracaceae and related families 183 Hallier's and Hutchinson's suggestions: Linaceae s.l. and Malpighiales 184

Pierre's view: Sterculiaceae and other Malvales 185

General Conclusions *9°

Acknowledgements 19°

References 191

families Index to original observations in other 192

Summary

seed and of and Vegetative anatomy, fruit and structure, pollen morphology Hua Afrostyrax (tropical in anatomical characters West and Central Africa) are described detail. The two genera have many in

182) but are sufficiently different from other families to common (see anatomical family diagnosis on p. discussed and the results of justify the existence of the family Huaceae. Some characteristic features are is comparisons with representatives of about 50 families are reported. Afrostyrax notrelated to Styracaceae, Sterculiaceae and Bombacaceae nor is Hua to Erythroxylaceae as had been suggested in the past. appear to

have the highest number ofcharacters incommon with Huaceae of all the families compared. This supports original obser- the inclusion of Huaceae in the Malvales as advocated previously by several authors. Some

of the families are included in the vations on the anatomy of a few compared comparative part.

Introduction

The Hua and from West and Central Africa consist two genera Afrostyrax tropical local because of the ofshrubs or trees which are used by the population as a spice strong

l 18: ) Part I was published in Blumea 369 —391, 1970. 162 BLUMEA VOL. XX, No. I, 1972

& garlic flavour of their young leaves, bark and seeds (Mildbraed 1913, Walker Sillans

1961, Germain 1963). be Their taxonomic history is rather confused. They have been considered to closely

related to each other by several authors, whilst others maintain that they should be

placed in families of different orders. from Hua was described the Congo by Pierre in 1906 as a member of Sterculiaceae.

Features aberrant for the family induced him to create a new tribe Huaeae. The external illustrated showed the less morphology was amply and peculiar more or peltate and

clawed petals, the 4-celled anthers and the unilocular ovary with one basal ovule.

Afrostyrax was first described from the Cameroons by Perkins et Gilg (1909), who

placed this genus in Styracaceae in a new subfamily Afrostyracoideae, being the only Styra- with caceous representative on the African continent. Features in common Styracaceae

such as resemblance in seed structure and stellate indumentum were emphasized and

Perkins exemplified the isolated position within the family by the calyx, fused in bud and

with the free the unilocular with 6 basal opening irregular lobes, fleshy petals, ovary smell of all of also Perkins ovules and the garlic parts the plant (see 1928). Mildbraed the first advocate the affinities of with (1913) was to Afrostyrax Hua in a

He paper on garlic barks of West Africa. furthermore added the important observation made close with the that Afrostyrax has early caducous stipules, which a relationship

In of the unilocular with basal exstipular Styracaceae more unlikely. spite ovary ovule(s)

he regarded it to be more closely related to Sterculiaceae than any other plant group. Hallier f. (1923) also indicated the affinities of Hua with Afrostyrax when he commented:

'Sie (Marquesia Gilg) scheint mit Monotes A. DC, Afrostyrax Perk, et Gilg und Hua

Pierre eine kleine Afrikanische Pflanzengruppe zu bilden welche die Linaceen-Houmi-

rieen mit den Tiliaceen und Dipterocarpaceen verbindet.' The Rijksherbarium contains

a sheet (Zenker 3992) of Afrostyrax kamerunensis with a note by Hallier f. ‘Huae arcte

Steenis Brink affinis’. This suggestion was supported by Van and Bakhuizen van den Jr. for and (1967), who also advocated a Sterculiaceous affinity Hua Afrostyrax.

Chevalier (1947) formally erected the family ‘Huacaceae’ in which he included the two

of 'une evidente' with he placed the family in Ebenales, genera. Because parente Styracaceae and the of from adding that Hua Afrostyrax constitute ancestors present day Styracaceae

Asiaand America. He also mentioned some points in commonwith Sterculiaceae, however. Shaw (1966, in Willis: Addenda XXi) also stressed the probable affinities of Afrostyrax

with Hua, but concluded that 'Pierre and De Wildeman's original suggestion of a Ster-

culiaceous affinity for Hua is almost certainly correct'. reserved rank for Different views came from Hutchinson (1959), who the family Hua

(Huaceae) in his Malpighiales close to Erythroxylaceae, and maintained that Afrostyrax

differs widely from Hua and should be retained in Styracaceae. W. Robyns (1958) in be revising Afrostyrax for the Congo, also arrived at the conclusion that this genus should kept in Styracaceae and that affinities with Hua are unlikely. Accordingly Germain (1963)

only considered Hua in his treatment of Huaceae in the Flore du Congo duRwanda et du Burundi.

Apart from the mutual affinities between Hua and Afrostyrax, the affinities with other of families remained controversial and enigmatic. Edlin (1935) in revising certain groups Malvales expelled Hua from that order because it showed 'no affinities whatsoever.'

Cronquist (1968) and Takhtajan (1969) admitted that the affinities of Huaceae are still obscure. Krause (1915) in Engler and Prantl's Nachtrage IV recognized Pierre's tribe

Huaeae, but Engler and Gilg (1919) placed both Hua and Afrostyrax in Styracaceae. In the the new Engler Syllabus (1964) both relationships between Hua and Afrostyrax and their affinities to Styracaceae are said to be uncertain. P. Baas: Affinities of Hua and Afrostyrax 163

The anatomy of both Hua and Afrostyrax has received little attention so far. Perkins

Befund fur noch eine (1909) stated only: 'Die anatomische spricht weder gegen Zuge- dasz horigkeit von Styracaceae, so ich hier nicht naher daraufeingehen mochte.' Dehay

(1941) briefly described the petiole of Hua. Mildbraed (1913: 557) gave a detailed de- of the bark of Normand and Chatelet scription Afrostyrax lepidophyllus. We owe to

(1955) a description of the wood of that species. They mentioned the great differences the and between woods of Styracaceae and Afrostyrax suggested a provisional placement

the need of of order to near Sterculiaceae, stressing a profound study Huaceae in gain more

insight into their affinities. Lebacq and Dechamps (1964) included Hua gabonii in their codified description of the woods of Central Africa. Their list of characters selected for

identification purposes does not allow, however, a detailed comparison with die available

data on Afrostyrax lepidophyllus. the A comprehensive study of anatomy of both genera was undertaken in order to

employ anatomical characters reliably in a discussion of both the mutual affinities and the

with other For this it found make relationships plant groups. purpose was necessary to a

study of leaf, twig, bark and wood anatomy, as well as ofpollen, seed and fruit structure. for the of acids A chemical test presence cyclopropene containing fatty (Halphen reaction)

was also carrried out. Other chemotaxonomic work is reported by Beijersbergen in the

present issue.

TECHNIQUES

anatomical studies of Techniques employed in the vegetative parts, flowers, fruits,

and seeds are the same as described before (Baas, 1970). Scanning Electron Microscope

(S.E.M.) studies were carried out with the Cambridge instrument ('Stereoscan') of the coated Department of Microscopy T.N.O., Delft, using gold herbarium specimens. In the order to reveal surface structure of stomata, the scales of Afrostyrax lepidophyllus were

off with adhesive Pollen made entire stripped tape. preparations were by acetolysing flowers the in usual way. The Halphen reaction was carried out on endosperm extracts

by Dr. H. W. L. Ruigrok from the Lab. voor Experimentele Plantensystematiek, Leiden, from the Nederlandse according to a recipe Farmacopee 1966: 447.

MATERIALS

the of the of the Herbarium the of the Through courtesy Director at Brussels, Keeper

Jodrell Laboratory, Royal Botanic Gardens Kew, the Forest Products Research Labora- and Breteler tory at Princes Risborough, Ir. J. J. Bos Ir. F. J. (Wageningen), Mr. J. Brookman-Amissah of the Department of Forestry, Ghana, Mr. R. Dechamps of the

Musee Royal de l'Afrique Centrale, Tervuren, Belgium, I obtained a wealth of her- barium material, wood samples, and some pickled material of flowers and fruits. Some of

the woodsamples were especially collected for this study by Bos, BretelerandBrookman-

Amissah. Specimens studied will be listed under the different headings of the descriptive

part. Most of the herbarium material used is from Brussels; Bos and Breteler collections

are at Wageningen.

SYNOPSIS OF THE FAMILY HUACEAE

the results of this short of the Anticipating study a description family Huaceae, consis-

ting of Hua and Afrostyrax, is given.

shrubs with Trees or simple, entire, alternate, stipulate leaves. Flowers actinomorphic, BLUMEA VOL. No. XX, I, 1972 164

in axillary few-flowered fascicles or solitary. Calyx either valvate and 5-merous or

fused in bud and lobes. Petals with short opening with 3—5 irregular 5, free, very or

long claws. Stamens 10, i-seriate, of equal length, anthers 4-celled. Ovary superior, conical Fruit unilocular with 1 or (5) 6 basal, erect, anatropous ovule(s) and a short style. dehiscent indehiscent Seed with a or capsule. 1 (or 2), copious endosperm. Embryo straight with obovate cotyledons.

RESULTS AND DISCUSSIONS

Taxonomical and macromorphological notes

In die past 5 specific names have been proposed: Hua gabonii Pierre ex De Wildeman,

H. parvifolia Engl, et Rrause (1911), Afrostyrax kamerunensis Perk, et Gilg (1909), A.

lepidophyllus Mildbr., and A. macranthus Mildbr. (1913).

H. parvifolia has been reduced to H. gabonii by Germain (1963) apparently because size and shape of the leaves show a continuous range of variation in Hua.

A. macranthus, described by Mildbraed from the Cameroons, agrees according to the

with A. for its description fully kamerunensis except narrower leaves, larger flowers, and of the denser indumentum pedicel and calyx. As for leaf shapes and sizes I found a con-

siderable range of variationin specimens whichbelonged undoubtedly to A. kamerunensis.

This character is therefore not valid in distinguishing A. macranthus from A. kamerunensis and it is possible that, like Hua parvifolia, A. macranthus should be reduced. W. Robyns

that (1958: 96) also mentioned ‘A. macranthus semble a peine distincte de A. kamerunensis’.

The of in presence early caducous stipules Afrostyrax was first reported by Mildbraed.

Chevalier and W. Robyns were unable to discover any stipules in the herbarium material

they studied. Of A. lepidophyllus I found a specimen (Congo, Gilbert 10308) with con- lanceolate shoot. The left the in spicuous stipules on a young scars by stipules Afrostyrax but their shoots indicated nodal are inconspicuous indeed, presence in young is by the anatomyof older twigs where short stretches of vascular tissue split off from each of the lateralnodal bundles the caducous There therefore to supply early stipules. are no reasons

to doubt Mildbraed's observations.

Glandular structures on the leaves of Afrostyrax have been reported by Normand and

Chatelet (1955) and Robyns (1958). Chevalier (1947) recorded them for the sepals of

The anatomical structure of the as described to Hua. glands on p. 178 applies essentially all of limited fruits glands independent where they occur. In the material offlowers and found raised disks the investigated these glands were in Hua as circular, slightly along

margins of the sepals. I observed a circular thickening around the basis of a developing in This seed Hua, composed of an epidermis with palisade-like cells and parenchyma.

thickening might also be glandular. In Afrostyrax glands can be found as raised disks the on margins of the petals and on the inner surface of the calyx, mostly overlying the distribution five major vascular bundles. On the leaves these glands have a different in each species. Hua has more or less crateriform circular glands scattered on the lower leaf

surface their most the leaf base. (Plate II: 3 & 4), occurrence being frequent near In

Afrostyrax kamerunensis the glands are oblong-oval structures along the leaf margin, the base again most numerous towards (Plate II: 6). In A. lepidophyllus the occurrence If the of glands is not a constant character. present they may be found on abaxial or adaxial surface of the leaf or along the leaf margin, in each case near the base of the leaf. One of the striking differences between Hua and Afrostyrax lies in the shape of the

petals. In Hua these are long clawed, with a hirsute ± peltate lamina. The petals of P. Baas: Affinities of Hua and Afrostyrax 165

consist Afrostyrax are not conspicuously clawed but they too of two parts: a very short and rather broad base obovate lamina. The ofseveralBuettnerioideae of supporting an petals

the Sterculiaceae (see Leinfellner, i960) recall those of Hua and Afrostyrax.

Ovary, Fruit and Seed Anatomy

Hua gabonii

Material: Donis Louis material of immature Congo, 3121 (dried fruit), 7287 (pickled fruit).

thick. and Pericarp glabrous, c. 0.7 mm Epidermis subsequent parenchyma layers (c . 3)

followed by zone of thick-walled densely pitted stone cells (brachysclereids). Inner part

parenchymatous and constituting the bulk of the pericarp, supplied with collateral vascular bundles. Testa from 3-layered, c. 0.5 mm thick, developing two integuments,

the outer integument giving rise to the outer parenchymatous testa, covered with thin- walled unicellular hairs and traversed vascular simple by numerous centric (amphicribral)

bundles. Outer epidermis of inner integument developing into lignified palisade cells

with thick cells cells divided a broad and densely pitted walls; c. 250 fi tall; some into

short inner and a longer and narrower outer cell. Remainder of testa parenchymatous,

of compressed in mature seed. Perisperm present in mature seed as very thin layer com- pressed parenchyma cells. Endosperm copious, composed of cells rich in starch grains and minute oil droplets. Embryo straight with two flat obovate cotyledons (6x5 mm),

adpressed to each other.

Afrostyrax kamerunensis (Fig. 1 & 2, Plate II: I)

Material: Congo, Gillardin 176 (dried flower), Louis 13877 (pickled flowers), Louis 7287 (pickled fruit).

Ovary pentagonal in transverse section, densely covered with stellate hairs. Ovary wall supplied with 10 vascular bundles, all ± collateral in Louis 13877 (fig. 1), only 5 collateral Gillardin the bundles the of the in 176, 5 at corners ovary as seen in transverse section with 2 lateral xylem poles (fused lateral bundles of 5-carpellate ovary?). Ovules central basal with adaxial and 5 or 6, erect on a placenta, anatropous, bitegmic, raphe abaxial micropyle. Pericarp densely covered with stellate hairs, c. 2 mm thick, interspersed with vascular bundles both and inner of on outer parenchymatous parts (fig. 2). Layer and of vascular elaborate and brachysclereids inner part pericarp as in Hua\ tissue more complex, however (fig. 2). Testa 3-layered as in Hua, c. 2.5 mm thick, glabrous; outer traversed parenchymatous tissue by amphicribral vascular bundles, c. 2 mm thick, paren- chyma cells opposite ridges of palisade layer with brown contents. Palisade layer of tall thick-walled and cells with and broad furrows densely pitted (c. 200/1 tall), narrow ridges surface in sectional view (fig. 2; Plate I: 1), and with reticulate sculpturing in view. Inner testa wholly parenchymatous; layers close to endosperm compressed. Remainder of seed as in Hua.

Afrostyrax lepidophyllus

The of fruit and seed has not been studied this with anatomy in species. As seen a stereomicroscope (magnification X 50) the structure is basically similar to that in A. kamerunensis for much thinner and the absence of reticulate in except a testa a sculpturing the palisade layer. 166 BLUMEA VOL. XX, No. I, 1972

— Figs 1 x and 2. Afrostyrax kamerunensis. — 1. transverse section ofovary, x 50. 2. section ofpericarp and

fruit ofcells with dark i: o: testa, x 17. — f: wall;g: groups contents; integument; ovule; p: palisadelayer, t: testa; vb: vascular bundle. Phloem dotted, sclerenchyma black, xylem hatched.

Pollen morphology

& Hua gabonii (Plate I: 1, 2, 3 4)

Material: Congo, Klaine 289s, Louis 2914, Robyns 1441.

Grains single, oblate, equatorial outline triangular to semitriangular, diameter 36—49

circular to oval — in mainly (mean 43) fx. 3-, rarely 2-porate. Pores (c. 3 5 fx diameter), endexinous, surrounded by annular thickening of endexine, virtually closed by ektexine and with of variable Endexine an operculum size. c. 1.5 fx, near pores 2.5—4 fx thick, sometimes into inner Ektexine differentiated a thin and a thicker outer layer. c. 1 /x thick, of of columellae and surface composed a layer short, densely spaced a tectum. Tectum areolate. Areolae diameter. finely verrucate to c. 0.5—1.5 /x in

Afrostyrax lepidophyllus (Plate I: 7)

Material: Evrard Gilbert Louis Congo, 4221, 10221, 13883.

Oblate dia- Grains as in Hua but smaller and with thinner exine layers. to suboblate,

— often indistinct. Endexine meter 27—33 (mean 31) /X. Pores 2.5 X 3 3 X 4 tx. Operculae thick. Ektexine almost in c. 0.5 fx, near pores c. 1 fx c. 0.5 fx thick, homogeneous optical section. Surface pattern very finely scabrate.

& Afrostyrax kamerunensis (Plate I: 5 6)

Material: Caraeroons, Zenker 3922; Congo, Gillardin 176.

Endexine thick. Ektexine thick. As in A. lepidophyllus. near pores 1—1.5 fx 0.5—1 fx P. Baas: Aβnities of Hua and Afrostyrax 167

show Note. Acetolysed grains of Hua and Afrostyrax often folds in a regular trian- of the Hua gular arrangement on one or sometimes both sides equator (Plate I). For

similar structures have been interpreted as colpi by Oltman (1971), who investigated one

sample from the Congo. His illustration is indeedsuggestive of colpi, but in most grains

I investigated, I found these structures less conspicuous and without 'smooth colpus

membranes'. Moreover, they are absent from a considerable number of grains (see e.g.

folds of the in Huaceae Plate I: 4) or are more irregularly arranged. Regular type as are

of common occurrence in triporate oblate grains (Mr. J. Muller, private communication).

Vegetative anatomy

Hua gabonii

Leaf & Plate & 1 (Fig. 3, 4, 5, 6, 9, 10, 11 12, I: 8, II: 3 4, III: & 2).

Material: Gillardin Congo, 353, Gillets.n., Louis 930.

In surface view. Unicellular adpressed hairs infrequently present on abaxial

surface, mostly branched with one short thin-walled and one long thick-walled arm

small (fig. 4). Stellate to peltate hairs very rarely present near leaf base. Wax present as the cuticle cells ofadaxial surface particles on (Plate III: 2). Epidermal rectangular to poly-

gonal; anticlinal walls sinuous at high focus and ± straight at low focus. Outer walls

with pit-like cavities between anticlinal wall undulations due to invaginations of the cell lumina the of the walls. cells of abaxial into inner part Unspecialized epidermis

similar but with pit-like structures present in the entire outer wall (Plate III: 1); anticlinal walls walls with ± straight; periclinal outer lowly papillate as seen S.E.M. (Plate III: 2).

Cells overlying major veins ± square to rectangular, arranged in rows. Stomata confined abaxial in minor to surface, abundant areolae and over veins, scanty over midrib and

major veins, paracytic with ± rectangular to high dome-shaped subsidiary cells and

narrow guard cells. Subsidiary cells and guard cells devoid of pit-like structures. Guard

cells with so-called T-piece at poles (see Stace, 1965; Plate III: 1). Diameterperpendicular the and midrib often of to pore 8—10fi. Stomata overlying major veins deviating types. in and with for the Venation pattern (as seen cleared leaves paradermal sections) reticulate characteristic greater part entirely closed, square to rectangular areolae, resulting in a Circular crateriform number regular pattern (Plate II: 3). glands present in varying on leaf base II: adaxial surface, most frequently near (Plate 3 & 4). Cuticle In transverse section. c. 1 u thick. Epidermal cells square to flattened, about cells ofabaxial smaller. adaxial cells of the same size as unspecialized side or slightly

Outer walls of abaxial epidermal cells convex to lowly papillate. For pit-like structures

above and & wall thickness in withother see fig. 3, 5 6. Outer 4—5 fi. Stomata ± one plane

cells, with well developed outer and inner cuticular ledges (fig. 5). Guard cells with

lumina that are slit-like in polar transverse section (fig. 6), triangular in median transverse

section and dumbell-shaped in sections parallel to the pore (fig. 3). Mesophyll composed of

and one layer of short palisade cells, fairly compact 'spongy' tissue of about 4 layers of

& with isodiametric, rounded, very slightly lobed cells. Midrib (fig. 11 12) slightly

convex adaxial surface and strongly convex abaxial surface, supplied with an abaxial

crescentiform adaxial vascular system and an almost flat vascular system, forming together

an almost closed cylinder sometimes enclosing an extra medullary bundle (fig. 12).

Whole vascular system sheathed by several layers of thick-walled sclerenchyma fibres.

Ground tissue of midrib parenchymatous, unlignified at periphery, lignified in 'pith' 168 BLUMEA VOL. XX, No. I, 1972

Hua of lamina. general omitted, x Figs. 3—6. gabonii, transverse section 3. view, spongy tissue 290; 4.

median section of 6. section of stoma, unicellular hair, x 290; 5. transverse stoma, x 440; polar transverse

— transverse of abaxial x — 8. A. kamerunensis, x 440. 7. Afrostyrax lepidophyllus, section epidermis, 440.

of base of lamina — Vascular of and transverse section through gland, x 50. Figs. 9—18. systems petiole and distal end of midrib (all x 50). 9, 13 and 16 through base of petiole; 10, 14 17 through petiole; 11, 12, A. 15 and 18 throughmidrib. 9—12. Hua gabonii (9— 11.Gillet s.n.; 12. Gillardin 355). 13—15 kamerunensis.

A. — b.s. bundle of 16—18. lepidophyllus. c: collenchyma; c.c. : cristarque cell; : sheath; g. ep. : epidermis

gland; i: pit-like invaginations of lumen into cell wall; ep.: epidermis; p: palisade chlorenchyma; p.c. : sectioned the sectioned h.: s : stoma to s : stoma densely pitted cells; p. papilla-like hair; x parallel pore; 2 hatched. perpendicular to the pore. Phloem dotted, sclerenchyma black, xylem P. Baas: Affinities of Hua and Afrostyrax 169

enclosed by vascular system. Lateral veins with single collateral bundles. Veins ranging

the minute veinlets of vertical of between following types: i) composed a row 3 or 4 lignified elongated parenchyma cells; 2) minor veins composed of several xylem elements adaxial of cells with each small accompanied by ab- and girders lignified parenchyma a

fibre strand and an ordinary parenchyma cell or cristarque cell (defined as cells with a and fibre partially thickened lignified wall containing one or more crystals) linking the and well strands to the epidermis (fig. 3), 3) larger veins with developed xylem and

phloem portions separated from abaxial and adaxial sclerenchyma strands by lignified the whole linked the parenchyma; system again to epidermis by ordinary parenchyma

cells cells Bundle sheaths or not differentiated. Fibres of or cristarque (fig. 3). hardly different strands accompanying vascular system often branched at junction of veinlets. end Petiole ± cylindrical; in transverse section through distal (fig. 10) supplied with large abaxial crescentiform strand accompanied by two adaxial bundles, at base of petiole bundles. Vascular (fig. 9) with vascular cylinder enclosing one or two medullary system

sheathed by collenchyma. Cristarque cells with rhomboidal crystals, present in ground of and sub- tissue of petiole as scattered idioblasts (Plate I: 8), in phloem rays petiole in

cells Glands similar to those described epidermal opposite veins (see above). in anatomy

on p. 178 for Afrostyrax kamerunensis.

Axis (Table I)

in Material: Congo, Gillardin 355, Gillet s.n., Louis 930. Young twigs 1—4 mm. diameter and twig of

10 mm diameter.

older Young twigs rounded-rectangular, twigs terete. Unicellular hairs as on leaf,

infrequent. Epidermis of ± cubical, axially slightly elongated cells, lost in twigs thicker

than differentiated in Gillardin of cells with adax- 3 mm. Hypoderm only 355, consisting ially thickened and lignified walls. Cork arising in subepidermal layer, composed of

cells which are rectangular in transverse and radial section and pentagonal or hexagonal walls. cork in tangential section, with thickened inner Several cells with brown contents.

of —8 of cells with idioblastic cells Cortex 5 layers parenchyma interspersed cristarque

(frequency variable). Endodermis only distinguishable by a higher proportion of cristarque

cells in this layer, followed by a perivascular cylinder of a mixture of fibres and brachy-

the of sclereids, many of latter crystalliferous. Secondary phloem composed sieve tubes,

companion cells, and parenchyma cells, traversed by narrow and broad rays; the latter

of more or less triangular and for a large part composed sclerified cells. Secondary xylem:

defined absent. Vessels but also in radial Growth rings poorly or diffuse, mostly solitary

of or between the of the multiples 2 3, typically more numerous in regions corners rectangular pith than in regions facing these corners (this only applies to vessel frequency

in first formed secondary xylem, not in more peripheral parts of thicker twigs). Vessels

round to oval in transverse section, mean tangential diameter of first formed vessels vessel member and also table Perforations 26— 307e, mean length 630 640/4 (see I). simple for in first in oblique end walls, except very scanty scalariform perforation plates some formed vessels. Lateral wall secondary xylem pits opposite to alternate, round, oval, or

transversely much elongated with horizontal to oblique slit-like apertures; vessel—paren-

and sometimes unilaterally compound. Round c. 2 in chyma vessel—ray pits pits —3 fi

diameter. Vessel contents absent. Tracheidsin association with vessel mutiples, infrequently present. Fibres constituting ground tissue of secondary xylem, with thick walls and

minutely bordered to simple pits. Parenchyma mainly paratracheal in short irregular in bands in first formed secondary xylem; later formed wood more regularly banded. No. 170 BLUMEA VOL. XX, i, 1972

TABLE I: Vessel member length in Hua and Afrostyrax (in μ).

Material twigs near pith of trunks peripheral wood (at least from 2.52.5 cm from pith)

mean mean mean range mean range mean rangerange

HuaHua gabonii

Gillet s.n. 640 210—860

Louis 930 630630 390—920

of Breteler 6677, upper partpart stem 860 560—1130 940940 620—1280

— 860 ibid, middle partpart 780 410 960 860 570—1340570—1340 ibid,ibid, basal part 820 370—1130370—1130 880 670—1550

Dechamps 172172 750 520 —1150—ii 50

Dechamps 296 740740 460460— 860

Dechamps 363 640 310— 800

Afrostyrax lepidophyllus

2661 Devred 430 170—740

Brookman Amissah — s.n. 650 390—390 950 730 580—1030 —1080 G.C. 57735773 770 520520

Afrostyrax kamerunensis

Evrard 28382838 570570 410410—750—750

Gillardin 176 470 190—720 of in Louis 5611 670 460—930 (peripheral part twig, i1 cm in 0)

Bos <320620 7155 770 540 —1030 no—no—11301130

Bos — — Bos 7287 830 520520—11401 140 710 520520— 930

Bos 7205 730 540—1080 720 460—1130—iI30

and 20. of bark, — — Hua Figs 19 Transverse sections x 17. 19. Afrostyrax lepidophyllus. 20. gabonii. c: cork; r: rays. Sclerenchyma (stone cells and/or fibres) black. P. Baas: Affinities of Una and Afrostyrax 171

of of material of two Rays 12—17/mm at periphery secondary xylem investigated,

distinct sizes: uniseriate of and tall rays, narrow, mainly rays upright cells, broad, very sheath cells heterogeneous, composed of square central and upright marginal cells; some

also in bundles at of central ray portions upright. Primary xylem present 4 major corners the with in Node of quadrangular pith a varying number of smaller bundles between. and smaller lateral off the trilacunar with one major median bundle two bundles, split each.Pith vascular cylinder.Lateral bundles forked to supply stipules withone vascular strand

quadrangular in transverse section, composed of parenchyma cells which are isodiametric in and polygonal in transverse, rectangular in longitudinal section; cell walls lignified cells of older twigs. Solitary rhomboidal crystals present in varying amounts in cortex, and perivascular sclerenchyma, phloem, secondary xylem rays, pith. The crystalliferous cells cells. cells include unlignified or lignified parenchyma cells, stone and cristarque of Many of the crystalliferous cells of the pith in longitudinal pairs due to subdivison a thin and with unilateral wall 'cham- pith cell by a transverse wall, lignified thickening:

bered cristarque cells'.

Bark (Fig. 20)

Breteler of Material: Gabon, 6677 (from stem c. 5 cm diameter).

General features. Colour very light brownish grey; c. 1—2 mm thick; outer

with cracks in surface partly smooth, partly narrow longitudinal periderm. features. Cork of of flattened cells with faintly Microscopic many layers

cork cells with brown contents. thickened and lignified inner tangential walls, some of the

in Perivascular of and less Cortex as young twigs. cylinder mainly brachysclereids numerous well of sieve fibres developed, c. 0.5 mm thick. Secondary phloem tubes, companion and small cell traversed and cells, parenchyma, cristarque cells, stone groups, by narrow broad rays. Broad rays triangular in transverse section, with strongly sclerified parts rhomboidal obscuring the dilatation pattern of the rays (fig. 20). Solitary crystals present and in cristarque cells and parenchyma cells of cortex phloem and in some brachy- the in of the cork sclereids of perivascular cylinder and rays. Smaller crystals present some and cells. Very irregular clusters of variable size also infrequently present in cortex phloem.

Wood (Plate IV: 1 & 2, Table I)

middle and of in diameter and Material: Gabon, Breteler 6677 (basal, upper part stem c. $ cm 1.4 m long); & Congo, Dechamps 172, 296 363 ex Tervuren (samples from thicker stems).

General features. Wood heavy and hard. Colour light brownish yellow.

Growth rings faintly demarcated at irregular intervals. Vessels, broad rays, and numerous Heartwood demar- tangential parenchyma bands visible to the naked eye. brown, poorly cated from sapwood.

2 Microscopic features. Growth rings indistinct. Vessels diffuse, 9—16/mm in

2 mature wood samples, 32/mm in periphery of small stem from Breteler 6677; solitary and radial clusters of vessels vessel in multiples or 2—5. Ratio solitary to groups ranging

— Vessels round oval in transverse from 4:1 (small trunk) 1:2 (generally 1 :1). to

diameter mature section (radially elongated); mean tangential no—165/.i in wood, 75 ji

Breteler radial diameter to 280 walls —8 thick, mean vessel member in 6677, up fi\ 4 jx

for mature wood, for Breteler (Table I). Perforations length 640—750 n 860—940fj 6677 simple in horizontal to slightly oblique end walls. Lateral wall pits alternate. Intervessel No. 172 BLUMEA VOL. XX, I, 1972

round to in diameter with slit-like and horizontal pits polygonal, 5 —9[i ± apertures,

mostly enclosed within the pit borders, occasionally extending over several pits (coales-

cent), giving the impression of being vestured in vessels with contents. Vessel—ray and

vessel—parenchyma pits similar but half bordered, sometimes slightly smaller and occasionally unilaterally compound. Tyloses absent. Solid amorphous light brown

in heartwood Vascular tracheids associated with contents present some of the vessels. some Ground of thick-walled of the vessel multiples, sparsely present. tissue composed fibres radial minute with few simple pits which are mainly confined to the walls; some pit Fibres radial which disturbed borders present in Breteler 6677. arranged in rows are by

rounded diameter 20 walls intrusive growth, hexagonal to in transverse section, —30 [i, lumina in tangential 5 —15/ji thick; very narrow, mean length 1760—1950//. Parenchyma

more or less continuous bands in which the vessels are (mostly completely) embedded

bands cells wide and at variable (confluent paratracheal), I—3 (or 4) distance(ioo—350/t) bands of of from each other; subsequent linked through paratracheal parenchyma some radial vessel strands of cells. the multiples. Parenchyma 6—12 (mostly 8) Rays 9—11/mm, of distinct —20 cells composed two sizes: narrow rays 1- or 2 (or 3)-seriate, (1—)3 high, of cells and broad or) —15-seriate, to mm high, composed square to upright rays (4 5 up 3

cells with to of mainly procumbent square to upright marginal cells; some square upright sheath cells also Chambered cells present. crystalliferous in various frequencies present confined strands fibres. of the cells of in parenchyma bands, to touching on Only part a

parenchyma strand subdivided into chambers, each with a solitary rhomboidal crystal also and wall thickening where touching on the fibres. Prismatic crystals infrequendy

Silica bodies absent. present in ray cells.

Afrostyrax lepidophyllus

Description gives only points of difference with Hua.

Leaf & Plate II: & & (Fig. 16, 17 18, 2 5, III: 3 4)

Louis Material: Congo, Devred 2661, Gilbert 10508, 350.

In surface view. Peltate scales covering abaxial surface, with several-celled stalk of inserted between a rosette 6—8 small, often cutinized cells (Plate III: 3 & 4). Scale

cells long and fusiform, not subdivided, attached to each other for more than half of

their lengths (Plate II: 2). Diameter of scales 120—260 u. Stellate hairs present on petiole.

Short dome-shaped 2- or 3-cellular hairs resembling papillae also present on abaxial

surface (Plate III: 4). Wax absent. Epidermal cells ofadaxial surface rectangular to polygonal

with anticlinal walls slightly sinuous at high focus and straight at low focus. Outer walls

without pit-like structures. Cells overlying veins as in Hua. Epidermis of abaxial surface almost entirely composed of specialized cells apart from cells overlying major veins of the adaxial surface. Remainder of short which are similar to those composed papilla-

like hairs, scales, subsidiary cells and guard cells of stomata. Stomata raised above abaxial

minor midrib and leaf surface, very numerous in areolae and over veins, scanty over

major veins, paracytic with crescentiform subsidiary cells (Plate III: 3) and low dome-

shaped guard cells. T-piece at poles of guard cells inconspicuous. Lumina of guard cells

to the in Hua as in Hua (fig. 7). Diameter perpendicular pore 9—11 fi. Venation pattern as (Plate II: 5) but areolae slightly smaller. Glands often absent, if present confined to basal smooth circular oval abaxial adaxial surface the part of lamina as or areas on or or along leaf margin. P. Baas: Affinities of Him mid Afrostyrax 173\I

Klaitie in x I. Hua — Plate 1—4. gabonii. I. 285g , pollen grain optical section, 1000; ia. ibid., showing view pore, operculum and exine layers, x 2000; 2. Robytis 1441, polar showing areolate pattern, x 1000; 3.

without folds in x — and 6. ibid., poral view, x 1000; 4. ibid., grain exine, 1000. 5 Afrostyrax kamerunensis.—

in 6. — A. 5. Zenker 3922, pollen grain optical section, x 1000; Gillardin 176, poral view, x 1000. 7. lepi- dophyllus, Louis 13883, pollen grain in optical section showing operculae. — 8. H. gabonii, cristarque cell

x — A. axial wood cells, from ground tissue of petiole, 840. 9. lepidophyllus, crystalliferous parenchyma x 840. BLUMEA VOL. No. 174\II XX, i, 1972

II. section and cells with dark contents Plate 1. Afrostyrax kamerunensis, of testa showing palisade layer

with (arrow) in outer testa, x 100. — 2. Afrostyrax lepidophyllus, leaf scale partly covered fungal hyphae,

x x detail S.E.M., 150. — 3 and 4. Hua gabonii. — 3. cleared leaf showing venation and glands (arrow), 6; 4.

A. x 6. — A. — cleared cleared of crateriform gland, S.E.M., x 100. 5. lepidophyllus, leaf, 6. kamerunensis,

6. leaf with marginal gland (arrow), x P. Baas: Affinities of Hua and Ajrostyrax 175\III

III. Plate Abaxial epidermis as seen with the light microscope (1, 3 and 5; all x 420) and the Scanning

and x and in Electron — Microscope (2 4, x 500; 6, 750). 1 2. Hua gabonii; note pit-like structures unspecial-

in — and ized epidermal cells (partly retouched) in 1, and wax particles 2. 3 4. Afrostyrax lepidophyllus; hair in A. bases — and kamerunensis. note (arrows). Fungal hyphae present 4. 5 6. IV. and Plate Wood anatomy ofHua gabonii (1 and 2) Afrostyrax lepidophyllus (3—7). 1, 2, 3, 4 and 7, x and — intervessel — — 42; 5 6, x 420. 5. pits. 6. vessel—ray pits. Note crystalliferous parenchyma cells (arrows) in radial section (7). Hua P. Baas: Affinities of and Afrostyrax 177

In transverse section. Cuticle less than i// thick. Epidermal cells of adaxial surface those of adaxial surface another ± square, papillose or specialized in way (see above and and smaller than adaxial cells. Outer wall thickness Guard cells fig. 7) c. 2 //. of raised stomatal stomata slightly over subsidiary cells; complex like in Hua for other characters tall and (fig. 7). Mesophyll composed of 1 or 2 layers of palisade cells, loose to of isodiametric lobed fairly compact spongy tissue slightly cells. Midrib shallowly grooved or almost flat adaxially, strongly raised above abaxial surface, supplied with a flattened cylindrical vascular system enclosing 2 or 3 medullary bundles; for the rest as lateral also with of in Hua (fig. 18). Major veins provided a vascular cylinder. Veins higher order essentially similar to those ofHua but differing in the following characters: 1) adaxial girders linking sclerenchyma strands with epidermis taller and composed of several cells of narrow diameter, some of which are cristarque; 2) bundle sheath fairly conspicuous, often containing cristarque cells with the lignified wall thickenings on the side of contact with the vascular bundle. Petiole more or less as in Hua, degree of com-

16 plexity of vascularization variable, e.g. like in fig. and 17. Cristarque cells present in tissue of in of ground petiole and midrib as scattered idioblasts, phloem rays petiole, and in lamina in bundle sheaths and adaxial and abaxial girders linking sclerenchyma strands with the epidermis. Crystals rhomboidal or of irregular shapes, more rarely clustered, confined cells. Glands if similar those of mostly to cristarque present in anatomy to A. kamerunensis (p. 178).

Axis (Table I)

Louis in Material: Congo, Devred 2661, 350. Twigs 4 and 7 mm diameter.

Stellate hairs the the leaves of (of same type as on A. kamerunensis)i) present on young twig. Epidermis, cork, cortex and perivascular cylinder as in Hua, tangential wall thickenings ofcork cells confined inner cell of however. Broad in to layers periderm, rays secondary phloem not sclerified, accompanied on both sides by groups of fibres surrounded by a

in sheath of cristarque cells. Secondary xylem ± as Hua. Vessel multiples of up to 10; frequency of vessels in first formed secondary xylem independant ofposition with regard to diameter of first formed vessels and mean quadrangular pith, mean tangential 30 33 pi, vessel member length 430/4 (Devred 2661). Meanfibre length 950/4 (Devred 2661). Paren- chyma more abundant than in Hua. Rays 12 and 16/mm respectively.

Bark (Fig. 19)

281 of in Material: Congo, Michelson ; Ghana, Brookman Amissah s.tt. (bark young stems c. 5 cm diameter).

General features. Colour brownish thick. light green to grey; c. i—3 mm See also Mildbraed (1913). features. Cork but adaxial wall confined Microscopic as in Hua thickenings to inner cell layers. Some parenchyma cells of secondary phloem with brown contents.

Groups of 2—10 fibres sheathed by strands of chambered cristarque cells lining the borders of the broad rays (fig. 19).

Wood (Plate I: 9; IV: 3, 4, 5, 6 and 7, Table I)

in Forest Material: Ghana, Brookman Amissah s.n. (stem 5 cm diameter), Ghana Dept. G.C. 5773, sample from mature tree.

12 178 BLUMEA VOL. XX, No. I, 1972

General features. Colour somewhat darker than in Hua; growth rings and heartwood not differentiated in material investigated.

2 Microscopic features. Vessels 11 and 12/mm ratio solitary vessels to vessel , and diameter 80 groups 2 : I (small stem) I : I (mature wood), mean tangential /1 (small

and radial diameter to member and stem) 145 /x; up 220/i, mean length 730 770ji(Table Vessel I). contents infrequently present, also in peripheral secondary xylem. Mean fibre and with abun- length 1890 (small stem) 2260/u. In G.C. 5773 peripheral zone extremely broad cells dant parenchyma noted. Rays c. ii/mm, rays up to 4.5 mm tall and up to 10 wide.

Afirostyrax kamerunensis

Description gives only points of difference with A. lepidophyllus.

Leaf (Fig. 8, 13, 14 & 15, Plate II: 6; III: 5 & 6)

Material: Congo, Evrard 2838, Gillardin 176.

surface Stellate In view. hairs (occasionally tending to peltate scales) scarce on adaxial side of leafbase and petiole. Papillae and papilla-like hairs absent. Unspecialized epidermal cells with markedly sinuous anticlinal walls (Plate II: 5). Outer anticlinal walls of cells also sinuous. Diameter of to the —12 subsidiary stomata perpendicular pore 9 fi. than Venation pattern with more open veinlet endings in A. lepidophyllus (Plate II: 6).

Glands confined to leaf margin and narrowly oval in outline, mostly larger than those of

A. lepidophyllus and Hua.

In transverse section. Stomata in about the same plane as other epidermal

with cells. Major lateral veins only provided a single vascular bundle. Parenchymatous girders of minor veins shorter than in A. lepidophyllus due to the leaf being thinner and containing less cell layers in the mesophyll. Bundle sheaths without cristarque cells.

of less & of Vascular system petiole complex (fig. 13 14). Glands similar to those Hua and A. lepidophyllus, composed of palisade-like thin-walled epidermis cells. Tissue underlying glandular epidermis composed of several layers of densely packed cells with lignified abundantly pitted walls (fig. 8).

Axis (Table I)

Material: Evrard Gillardin and Louis of —8 in diameter. Congo, 2838, 176 5611. Twigs 1.5 mm

most details similar vessel member In to A. lepidophyllus. Mean length 470—670 //. Only in Gillardin 176 few scalariform perforation plates noted.

Bark

Bos in Material: Cameroons: 7133 and 7287 (barks of young trunks, 5 cm diameter).

Bos in details A. far fibre 7287 similar most to lepidophyllus,; Bos 7153 exhibiting less the and therefore the bark of the material groups in secondary phloem resembling Hua The of of studied. amount differentiated sclerenchyma might be a matter developmental

in of the fact that all material studied had the diameter. stage, spite approximately same

More material of Hua should be studied in order to assess whether fibre groups differen- tiate in more mature bark. P. Baas: Affinities of Hua and Afrostyrax 179

Wood (Table I)

Bos in sections Bos Material: Cameroons, 7155 (young stem, 5 cm diameter, and macerations), 7205 and

7287 (stems 5 cm in diameter, macerations only).

Agrees with A. lepidophyllus (young stem, Brookman Amissah s.tt.) in almost all details. member Mean with abundant Mean vessel length 780 fi. fibre length 1720/r.Peripheral zone

broad mm parenchyma (as in A. lepidophyllus:: G.C. 5773). Rays c. 13/mm, rays up to 4 in with high and up to 8 cells wide; peripheral zone abundantparenchyma much broader

conversion of fusiform initials into initials. due to ray

The Halphen reaction

Material: Hua gabonii, Cameroons, seeds collected by the local population for flavouring food (legit

Breteler); Afrostyrax lepidophyllus, Ghana, Flora of Gold Coast 3818 (Coll. Andoh).

The Halphen reaction was negative.

Discussion of some of the characters of Huaceae

The structure of the unilocular in is revealed its Ovary. 5-merous ovary Afrostyrax by be fused lateral bundles. supply of 10 vascular bundles, five of which to interpreted as

trace In a young ovary of Hua I could only 3 vascular bundles all on one side of the

Hua with five pentagonal ovary. However, the dehiscence of fruits valves also suggests a

structural basis of the These considerations of taxonomic 5-merous ovary. are importance of for comparisons Hua and Afrostyrax with putative relatives, since they remove objec-

with families a 5-carpellary tions against affinities showing ovary.

of Ovule and Seed structure. Bitegmic ovules of which the outer epidermis the inner number of families integument develops into a sclerenchymatous palisade layer occur in a which of the Malvales. the (Netolitzky), among are the major families In comparing seed of and with of oil seeds from anatomy Hua Afrostyrax descriptions by Vaughan (1970) the Sterculia 50 different families, closest resemblance was found in seed structure of exhibits (p. 245 I.e.). The layer of palisade cells in Sterculia, like in other Malvales, a zone where the lumina of the cells are wider than elsewhere. This zone is absent, however, in the seed of Hua and of Afrostyrax. The seed structure of Ricinus (Euphorbiaceae) is also Huaceae-like. the of vascular the quite It differs, however, in presence tissue in inner of the the is the in Hua parenchymatous layers testa, instead of in outer layers as case

of seed is still and Afrostyrax. Unfortunately our knowledge anatomy very fragmentary the and use of anatomical characters of the seed for taxonomic purposes can only yield

If additional suggestions for affinities. sufficiently known they can serve as well as any other character in of this complex confirming or denying relationships (see e.g. p. 184 where its paper Irvingia is excluded as a close relative, amongst others because of seed anatomy).

characterized their three Pollen morphology. The grains of Huaceae, by pores, usually provided with operculae and a finely verrucate to scabrate ektexine sculpturing are sufficiently distinct and unusual to offer a character complex of taxonomic significance. the characters will be included the discussion of In comparative part pollen in some been putative relatives. Comparisons with pollen from other families have very limited. BLUMEA VOL. XX, No. i, 1972 180

Erdtman's of of numberof In studying descriptions representatives a great families, some striking similarities were found with the triporate grains of Helicteres (Sterculiaceae). In the ofthis pollen slides, grains genus were also found to have endexinous apertures and an annular endexinous thickening near the pores. Operculae are, however, not differentiated

is and the tectum slightly different. No very striking resemblance was found with pollen of other families described conclusions types by Erdtman, but on the grounds of palynol- here ogy offered are only tentative because of the very incomplete comparison. the but I Oltmann recently reported on pollen morphology ofHua, disagree with his

view in addition the three the show six that, to porate apertures, grains colpi (see p. 167). This also implies that I do not see any reason to link Huaceae with Olacaceae, as was

tentatively suggested by Oltmann. Neither the pollen morphology of this family as described floral wood and leaf lend by Erdtman, nor morphology or anatomy support to

this view.

Indument. Edlin(i935) based his exclusion of Hua from Malvales partly on the simple

Hua hairs of as contrasted with the typically stellate indumentum of representatives of the Malvales. This becomes invalid after the observation of stellate hairs argument some the leaves of and the abundant of this hair on Hua (see p. 167) occurrence type in Afro- kamerunensis. Scales be styrax of the type encountered in A. lepidophyllus would also in line with Malvalian affinities, since the Durioneae of the Bombacaceae and some other

hairs Malvales exhibit a similar indumentum. The unicellular of Hua with one very short and similar one long arm are to thosereported by Heinzelmann and Howard for Icacina- who called them hairs because for of ceae, Icacinaceous they were typical a majority of this This hair also and other representatives family. type occurs in Malpighiaceae some

families (Metcalfe and Chalk; Uphof et al.) where it is intermediate between simple and

2-armed also types occurring in those families.

Glands. Extra floral nectaries have been recorded for 25 families by Metcalfe and Chalk. the Those ofBombacaceae, Malvaceae, and Sterculiaceae are different from glands in Huaceae,

since they are formed by assemblages of trichomes (see also Schnell, et al.). The glands of

Hua and Afrostyrax recall those of Dipterocarpaceae, Euphorbiaceae, Malpighiaceae, Passi- and their The of floraceae, Rosaceae (Schnell et al.) in anatomy. haphazard occurrence

these glands throughout the Dicotyledons suggests that they are of restricted taxonomic

value in discussions on relationships ofhigher taxa. However, their structure and occur- and the mutual affinities between the rence in Hua Afrostyrax support two genera.

The Venation pattern. very regular venation pattern in the leaves with rectangular all character areolae, almost completely surrounded by veinlets, is a very striking of both

Hua and Afrostyrax. In making miscellaneous comparisons and going through Etting- housen's classical works could find (1858, 1861) on venation patterns, I not any taxon Theo- exhibiting the same regular meshwork. The closest approximation was found in broma and of the Sterculiaceae. there far vein Scaphopetalum However, are more open

endings and the areolae are larger and have more irregular shapes in these genera than in

Hua and Afrostyrax.

Stomata and other epidermal characters. The potentialities and limitations of both

light microscopy and scanning electron microscopy for the studies of epidermal structure well illustrated Plate are by III: I—6. Features such as anticlinal wall undulations, pit-like

structures and of cells demonstrated with (in Hua), arrangement subsidiary are clearly P. Baas: Hua and Affinities of AJrostyrax 181

light microscopy but do not or hardly show up in S.E.M. studies. On the other hand,

the of in Hua could not be demonstrated presence waxy particles ligh t-microscopically.

The of wax assessed after the work had revealed the presence was only S.E.M. particles

(Plate III: 2), by applying local heat to the leaf surface after which a shining patch of

melted and resolidified wax became visible.

The taxonomic significance of the type of stomata for comparing taxa of higher rank remains uncertain. In is many cases our knowledge only limited to a few representatives of and for families several have been recorded also a given family many types (see p. 189).

Petiole anatomy and cristarque cells. The similar complex petiole vasculature in both Hua and Afrostyrax provides an additional argument to regard these two genera

in as mutually closely related. There are several families which a more or less similar type of those and Tiliaceae petiole anatomy occurs. Amongst are Bombacaceae, Sterculiaceae, of the Malvales canals almost (Dehay, 1941; Havez; Herlemont). Mucilage always present

in the petiole of members of those families are, however, absent from Huaceae. of Although the cristarque cells Hua and Afrostyrax occur in different parts of the plant, Metcalfe Chalk list they are most conspicuous in the petiole. and cristarque cells for and of only three families: Melastomataceae, Ochnaceae, Scytopetalaceae. In the course my

in Baas studies I also found them Bombacaceae (Coelostegia, see 1972), Irvingiaceae (or Irvingioideae of Ixonanthaceae: Irvingia and Klainedoxa), and Pandaceae (Panda). Probably their they are of more common occurrence than is known at present. Yet restricted

occurrence remains of diagnostic value, and if sufficiently substantiated by other

characters their different taxa additional evidence for mutual presence in two may provide Hua relationships as between and Afrostyrax.

Bark anatomy. The dilatating rays of the bark of Hua and Afrostyrax are a notable

26 character. Zahur (1959) recorded dilatating rays for families out of 85 investigated.

The triangular rays are in Bombacaceae, Malvaceae, Sterculiaceae, and Tiliaceae always non-fibrous accompanied by a conspicuous stratificationinto fibrous and portions of the remainder ofthe bark and this differ from these Malvales. tissue in respect Huaceae More- and over, mucilage canals, generally present in Malvalian barks (not in Elaeocarpaceae

Scytopetalaceae, however) are absent in Hua and Afrostyrax.

Wood vessel member The woods of Hua and anatomy, length. Afrostyrax are more

or less identical anatomically. They combine some specialized features such as simple

vessel perforations, libriform fibres, and confluent parenchyma, with less advanced

characters such as heterogeneous rays, long parenchyma strands, and vessel members

which are of medium length or moderately long. In table I the measurements for vessel

member length are given. Two points are ofinterest here: firstly that the vessel members of of of twigs are generally shorter than those first formed secondary xylem trunks and, kamerunensis and secondly, that in Afrostyrax (Bos 7155, 7205 7287) the peripheral vessel

members of the more mature wood are shorter than the first formed secondary xylem

vessel members near the pith. This is a reversal of the trend, always reported in literature,

that vessel member length increases from the pith outwards (Bailey and Tupper, and this also in of many others). In respect it is noteworthy that peripheral young stemwood

Hua gabonii (Breteler 667y) vessel members were found to be considerably longer than in

mature and The of the more samples (Dechamps 172, 296 363). significance great variation

in vessel member length in Huaceae is not yet fully understood. On some herbarium

labels the growth habit of Hua and Afrostyrax is described as liana-likeand the variable 182 BLUMEA VOL. XX, No. I, 1972

for of the in vessel member habit of the two genera might account part great plasticity ength.

The combination of xylem characters of Hua and Afrostyrax plays an important part of this because of the well established taxonomic value in the comparative section paper, of wood anatomical features and the large body of information readily available on this

subject for other plant groups.

The Halphen reaction. The negative result of the Halphen reaction for Hua and If the had been Afrostyrax; has no implications oftaxonomieimportance. outcome positive,

indicationof Malvalian would have been a very strong affinity given (Hegnauer, 1964: 286). Thenegative result does, however, notimply that Huaceae are notrelated to Malvales. since a number of undisputed Malvalian plants also lack the cyclopropene containing fatty acids in their seeds (Blackwell et al.) and are therefore negative for the Halphen reaction (Ivanow, 1927).

of the Hua and Afrostyrax as related genera family Huaceae

resemblance between and From the descriptive part an overwhelming Hua Afrostyrax from the fundamental in macromorphological becomes apparent. Apart agreement

stamens with characters such as the alternate stipulate leaves, 5-merous perianth, 8—10 with basal number of micro- 4-celled anthers, unilocular ovary ovule(s) etc., a great scopical characters are shared by both genera.

shared anatomical at the time The more striking characters, constituting same an anatomical diagnosis of Huaceae, are the following:

Fruit wall with outer and inner parenchymatous layers separated from each other by a layer of brachysclereids (stone cells). Outer testa parenchymatous, supplied with vascular and bundles. Inner testa with an outer sclerenchymatous palisade layer. Pollen triporate operculate. Stomataparacytic. Petiole supplied with ± cylindrical vascular system enclosing medullary bundle(s). Venationpattern of regularly arranged veinlets enclosing rectangular cells areolae. Leaf glands with palisade-like epidermis mostly present. Cristarque present. Bark with Node 3-trace, 3-lacunar. Solid perivascular sclerenchyma ring present in axis. narrow and broad triangular rays. Wood composed of vessels with simple perforations hetero- and alternate wall pitting, libriform fibres, banded paratracheal parenchyma and

geneous broad and narrow rays.

On the grounds of these shared characters, most of which are by no means of general and be occurrence within the Dicotyledons, Hua Afrostyrax must regarded as closely and wood related to each other. The anatomical resemblance in for instance fruit-, leaf-,

— other much than often encountered between two of on anatomy is greater genera The of those authors who maintain grounds — well established mutual affinity. views that Hua and Afrostyrax belong to different families and even orders (Hutchinson; Robyns) must therefore be rejected. Mildbraed's, Halher's, Chevalier's and Van Steenis' and

Brink's with mutual of the two Bakhuizen van den suggestions regard to relationships the anatomical evidence. genera are sufficiently proved by Chevalier with those The differences in external morphology as listed by together be used for These found in anatomical structure can profitably diagnostic purposes. differences of of cells wall undula- concern type indumentum, shape epidermal (anticlinal tions), girders of veinlets, and other minorcharacters (see descriptive part, p. 165—179). P. Baas: Affinities of Hua and Afrostyrax 183

with other Huaceae compared plant groups

the In following a summary will be given of comparisons made with the aid of data

from literature and observations of of about numerous personal representatives 50

dicotyledonous families. All families, in the past suggested by several authors as possible relatives, were includedand the comparisons were extended to all families of the order to which these families the of both Hutchinson belonged (following systems (1959) and Engler's Syllabus. Some families sharing striking anatomical features with Hua and also the families those Afrostyrax were compared. From compared, only groups with at

least a sensible claim for affinity will be discussed in this paper. Families which have been

connection with and loosely brought into Hua Afrostyrax, as for instance Icacinaceae, Olacaceae and have been but offer little Opiliaceae (Chevalier) considered they too resem- blance to be elaborately discussed. Comparisons with data from literature have often been restricted to textbooks like Engler's Syllabus (1964), Erdtman (1952), Hutchinson

(1959), Metcalfe and Chalk (1950), Netolitzky (1926), Solereder (1899,1908) and Vaughan

(1970). Additional anatomical monographic treatments have also been consulted. As far the extended slides as possible comparisons have been to microscopical of leaves, twigs, and wood from representatives of the families concerned. The slide collections of the

Jodrell Laboratory, Kew; the Forest Products Laboratories at Princes Risborough; the

Forestry School at Oxford; the Institute for systematic Botany, Utrecht, and the Rijks- been consulted for herbarium, Leiden, have extensively this purpose. with all studies As comparative based on microscopical characters, conclusions cannot

since be definite, the majority of species and a considerable numberof genera, particularly from the have been studied. be that large families, never It can only hoped in considering both anatomical characters and features these in macromorphological gaps our knowledge

will be more or less compensated for.

I have often used family names for disputed small groups. This has been done for

and does reflect practical reasons only not any personal opinion about the family rank of these groups.

Perkins’ and Chevalier’s View: Styracaceae and related families.

Perkins (1909) and Chevalier were struck by the resemblance of the seed structure and

the stellate indumentum of Afrostyrax kamerunensis with that of Styracaceae, and therefore the that in put genus into family. The number of characters Huaceae, differing from those

in substantial. The differences listed below Styracaceae is, however, remove any ground be related for regarding Afrostyrax or Huaceae as a whole to to Styracaceae.

Huaceae Styracaceae

Stipules present Stipules absent Corolla choripetalous Corolla sympetalous

Pollen 3-porate Pollen 3-colporate

Stomata paracytic Stomata anomocytic

Venation pattern with rectangular Venation pattern different

areolae

Petiole vasculature complex Petiole vasculature relatively simple

Node trilacunar Node unilacunar

cells cells absent Cristarque present Cristarque Cork arising in subepidermis Cork arising in pericycle BLUMEA VOL. XX, No. I, 1972 184

Vessel perforations simple Vessel perforations mainly scalariform

Xylem parenchyma banded Xylem parenchyma diffuse or in narrow

lines

in in Sarco- Styracaceae are most systems included Ebenales together with Sapotaceae, spermataceae, Ebenaceae, Lissocarpaceae, Symplocaceae, and Hoplestigmataceae (Engler's

Syllabus). Hutchinson maintains a smaller order Styracales. Neither the gross morpholo- gical characters nor the anatomicalstructure of the representatives of those families recall that affinities with Ebenales s.l. Huaceae, so are most unlikely.

Hallier’s and Hutchinson’s suggestions: Linaceae s.l. and Malpighiales.

Hallier's brief statement that together with Monotesand Marquesia, Hua and Afrostyrax

are more or less intermediate betweenLinaceae s.l. (Houmiriaceae), and Dipterocarpaceae and and Hutchinson's of both Tiliaceae, placement Hua near Erythroxylaceae, imply an

affinity of Huaceae with a group of families included in the Malpighiales by Hutchinson

in and the Geraniales in Engler's Syllabus. A brief summary of elaborate comparisons made with all families included in the Malpighiales by Hutchinson is given below.

Malpighiaceae do not recall Huaceae in their external morphology; differences inanatomy

be the vasculature of the the of may exemplified by simple petiole, arrangement xylem

parenchyma, and the usually narrow rays in Malpighiaceae. Houmiriaceae differ substan-

tially from Huaceae in their floral characters; their anomocytic or diacytic stomata, secondary xylem with scalariform vessel perforations and fibre tracheids also provide evidence that the two families are not mutually related.

Linaceae s.s. (excluding Ixonanthaceae, Ctenolophonaceae, Houmiriaceae etc.) show a

numberof differences in both floral structure and vegetative anatomy. The most impor-

tant anatomical criteria by which the family can be distinguished from Huaceae are the relatively simple petiole vascularization and the occurrence of fibre-tracheids in the distribution and secondary xylem. The parenchyma ray structure are also never quite as shows in Huaceae, though Hugonia some superficial histological resemblance in its wood.

The of different from those of pollen grains Linaceae are very Huaceae. Ixonanthaceae several Irvingiaceae, included in or even in Simaroubaceae (Rutales) by have authors, flowers which do not resemble those of Huaceae; their vegetative anatomy, offers in in however, a greatnumberof characters common: cristarque cells occur Irvingia

malayana Oliver (original observation), stomata are also paracytic, and the wood of and Klainedoxa resembles that of for the absence Irvingia Huaceae quite strongly, except in of very broad rays such as occur Hua and Afrostyrax (see Webber). Major differences of Irvingiaceae with Huaceae are the absence of medullary vascular bundles in the petiole,

the 3-colporate pollen grains, and the arrangement of tissues in the testa (Vaughan).

Ledocarpaceae, usually included in Geraniaceae, do not recall Huaceae in floral, pollen,

and vegetative anatomical characters.

Erythroxylaceae, stated by Hutchinson to be the closest relative to be found for Hua not

differs the in but also only from latter genus and Afrostyrax a number of floral characters,

lack resemblance in do not have closed vascular any vegetative anatomy. Erythroxylaceae a with bundles the cortical bundles in the axis, cylinder medullary in petiole, they possess and of and have a different type parenchyma distribution, ray structure, vessel—ray

pitting in the secondary xylem. The pollen is also very different. that in Ctenolophonaceae, often included in Linaceae but very different from family and and have wood anatomy pollen type (Metcalfe Chalk; Erdtman), primitive xylem P. Baas: Affinities of Hua and Afrostyrax 185

characters such as scalariform vessel perforations and fibre-tracheids. No characters from

vegetative anatomy, nor from floral morphology recall Huaceae. The Lepidobotryaceae are anatomically very imperfectly known. description given by

Metcalfe and Chalk (1950) does not recall Huaceae, nor do external morphological

in characters. Balanitaceae also differ widely gross leafand flower morphology. The wood

is also different in its storied and broad parenchyma exclusively rays. Zygophyllaceae have with anisocytic stomata.wood generally storiedstructure, fibre-tracheids, andnarrow homo- and differences in with Huaceae geneous rays, show many external morphology as well.

The Malpighiales, as understood by Hutchinson and discussed above in relation to

Huaceae. present anatomically a very heterogeneous assemblage and it is therefore impos-

sible to deny any affinities with the order on the grounds of anatomical characters. Each

family considered separately, however, is sufficiently different from Huaceae to deny close this affinity. It is significant in respect to stress that Erythroxylaceae, placed close to Hua

by Hutchinson, show no affinities in anatomical structure at all. Irvingiaceae, treated in

another order (Rutales) by other authors, show some rather striking resemblances in leaf and wood The differences external seed and anatomy. great in morphology, anatomy, rather than pollen type, however, suggest incidental convergence of some characters phylogenetic relationship.

Following the system given in Engler's Syllabus, Hallier's and Hutchinson's suggestions

would also validate a comparison with Limnanthaceae, Oxalidaceae, Geraniaceae, Tro-

paeolaceae, Euphorbiaceae, and Daphniphyllaceae, all included in Geraniales. Such compari-

sons are however, beyond the intentions of the two latter authors, and discussions of the

from will therefore be results these comparisons very limited. Limnanthaceae, Oxalidaceae, and Geraniaceae Tropaeolaceae are very unlikeHuaceae; the same applies to Daphniphyllaceae

It is which are characterized by a primitive wood structure. difficult to deny any relation-

ships with Euphorbiaceae on the grounds of anatomical characters because this family is

in very heterogeneous both leaf and wood anatomy. Several characters that occur like the of regularly in Euphorbiaceae type glands, petiole vascularization (Dehay 1935), and and seed anatomy are shared by Hua Afrostyrax. Wood anatomical characters of

if be in Huaceae taken one by one, can retraced different genera of the Euphorbiaceae, but a latter similar over-all histology has not been encountered in any representative of the

family. Differences in wood anatomy taken together with the great differences in floral

morphology therefore invalidate a close relationship between the two families.

with Hallier's further suggestion of a relationship ofHua and Afrostyrax Marquesia and

Monotes of the Dipterocarpaceae is not supported by anatomical characters such as the

uniseriate and the distribution in the woodof the latter rays parenchyma genera (Bancroft).

The pollen of Monotes with its colporate apertures is also different. Characters of other do Dipterocarpaceae also not recall Huaceae. Possible connections with Tiliaceae, implied in

Hallier's suggestion, will be discussed on p. 188.

from Summing up, only two families Malpighiales as conceived by Hutchinson or and from Geraniales as treated in the Engler's Syllabus, viz. Euphorbiaceae Irvingiaceae, show a number of striking characters shared with Huaceae. The characters in common

are, however, outweighed by points of difference, so that a close phylogenetic relationship

seems most unlikely (see also table II).

Pierre’s view: Sterculiaceae and other Malvales.

Pierre's of and the original placement Hua in Sterculiaceae, suggestion repeatedly put from forward that time, of a Sterculiaceous affinity for Hua and Afrostyrax (Mildbraed, BLUMEA VOL. XX, No. I, 1972 186

Huaceae TABEL II: Occurrence of some characters of in other families, mainly Malvales.

VI n 15 M 15 15 15 15 15 15 14

shared M Number characters M 5 (7) (5) (13) (6) (8) (6) of 3 VO C-> M S 5 4 $ 3 4 6

0 O rt O U n 0 O 8 Characters G 9 C8 ci a u 6 0 Huaceae n of CS ë "c Cochlospermaceae 0 Sphaerosepalaceae u J- Scytopetalaceae g n Sterculiaceae Euphorbiaceae Irvingiaceae Family 0 Malvaceae Tiliaceae « 53 00

unilocular _ ovary (+) (+) (+)

placentation basal — — — — ± — — — —

ovule and seed — — bitegmic with palisade layer + + + ? + + + pollen triporate (+) (+) scales or star-shaped hairs + — — + + + + (+) stomata paracytic (+) — — — — — — (+) — (+) venation pattern ± cristarque cells (+) + +

— petiole vasculature + — ± ± + + + + ± mucilage cavities absent — — + — — + (+) — + (+) dilatating bark rays + + ± + + — + + — ? libriform fibres + + (+) + ± + + + + + parenchyma paratracheally banded (+) + (+) — (+) — — +

broad and — — — narrow rays (+) + (+) + + (+) (+)

chambered crystalliferous cells + — + — + (+) + +

— = character = character = absent; 4- present in most representatives of the family; (+) character, present in a few representatives only; ± = tendency to be similar in this character; ? = no data available, n = number of characters recorded. Under 'number of shared characters' the figure between brackets represents the total number of +, (+) and ± characters.

Normand and Van Steenis 1913; Chatelet, 1955, and and Bakhuizen van den Brink, with 1967) induced me to make elaborate comparisons of Huaceae Sterculiaceae and other Malvales. Malvales taken the are here in broadest sense, including Bombacaceae, Dirach- maceae, Elaeocarpaceae, Malvaceae, Peridiscaceae, Sarcolaenaceae (= Chlaenaceae), Scytope- talaceae, Sterculiaceae, and Tiliaceae, together with Cochlospermaceae and Sphaerosepalaceae

(= Rhopalocarpaceae) which have been linked with Malvales in recent years (Capuron, This of the order does 1962; Huard, 1965; Keating 1968, 1970). concept Malvales not reflect any personal opinions but has been adopted for practical reasons in order to avoid the that relative of from the possibility a putative Huaceae might be missed out compari- sons.

Elaeocarpaceae show a greatnumberofdifferences in external morphology from Huaceae. do recall recorded Anatomically they not Huaceae either. Paracytic stomata have not been the for family and the parenchyma distribution in the wood is never in confluent bands. The pollen is also different. P. Baas: Affinities of Hua and Afrostyrax 187

in Scytopetalaceae, again very different external morphological characters, differ from Huaceae anatomically by the anisocytic stomata (original observation), the simple petiole vasculature, the sclereids in the leaf mesophyll, the occurrence of both scalariform and the the simple vessel perforation plates in mature wood, large and simple vessel—ray pits, and the axial parenchyma distribution in narrow lines. However, one very unusual character, the presence of cristarque cells, is shared by the two families.

Sphaerosepalaceae (= Rhopalocarpaceae) have been described anatomically by Boureau and by Huard, who considered them to be closely related to Malvales, particularly Sterculiaceae. order extend Huard's observations leaf of the In to on anatomy family some of original observations were made on material Dialyceras parvifolium R. Cap. (18126

S.F.), Rhopalocarpus louvellii (Danguy) Cap. (27563 S.F.), R. lucides Boj. (Lam & Meeuse

6116), and R. triplinervius Baill. (22963 S.F.) all from the Rijksherbarium. It appeared

in the that the petiole anatomy shows an even greater range of vascular patterns than material described Huard. shows closed vascular three by R. triplinervius a ring including in concentric (amphivasal) medullary bundles a horizontal plane whilst the other species and have closed vascular investigated by Huard me a or strongly incurved strand without additional bundles. Stomata, imperfectly described by Huard, were foundto be distinctly anisocytic in Dialyceras parvifolium and predominantly anomocytic (occasionally tending to anisocytic) in Rhopalocarpus. The seed structure of Rhopalocarpus (Capuron), though complex through rumination, is fundamentally similar to that in Huaceae, having a with the parenchymatous outer testa supplied vascular bundles separated from inner soft tissue by a layer of thick-walled sclerenchymatous palisade cells. Though I could not

the in it also study ontogeny Rhopalocarpus, seems likely that this palisade layer originated from the outer epidermis of the innerintegument, because of its position within the testa.

The wood of Sphaerosepalaceae (Boureau; Huard) is rather similar to that of Scytope- talaceae and does therefore recall that of (e.g. narrow wavy parenchyma bands) not

Huaceae. The differences between Sphaerosepalaceae and Huaceae in both floral structure of between and vegetative anatomy suggest therefore the absence close affinities the two be the of families. It may mentionedin passing, that the original observation on anatomy mentioned view Sphaerosepalaceae above, support Huard's and Capuron's of a Malvalian affinity of that family.

Dirachma, formerly included in Geraniaceae but raised to family rank by Hutchinson and under Neither floral placed inhis Tiliales, is at present myinvestigation. its morphology nor its leaf or wood anatomy recall Huaceae.

hi his also Peridiscaceae, recognized by Hutchinson as a distinct family Tiliales, are very different in external morphology and vegetative anatomy (e.g. in wood with scalariform vessel Peridiscus constituent often perforations). and Whittonia, their genera, are regarded as related to Flacourtiaceae (Sandwith; Metcalfe).

Cochlospermaceae, treated by several authors as belonging to the Parietales, Bixales, or them Violales, have been investigated in detail by Keating (1968, 1970) who regarded as more closely related to Sterculiaceae and Tiliaceae than to Cistaceae, Flacourtiaceae, and

the of wood Violaceae. Characters such as anisocytic stomata, presence mucilage canals, with very short elements, and apotracheal very thin-walled parenchyma, together with gross morphology exclude close relationships of this family with Huaceae.

Sarcolaenaceae of much affinities (= Chlaenaceae)J, a family disputed (Capuron, 1970, and the literature differs from in Cavaco, 1952 cited by them) Huaceae several characters of floral the the of morphology. Anatomically anomocytic stomata, presence mucilage cells, and the wood with diffuse apotracheal parenchyma and exclusively solitary vessels and uniseriate do also indicate Huaceae. The rays, not a close relationship with anatomy 188 BLUMEA VOL. XX, No. i, 1972

of the petiole and midrib is, however, very similar to that in Hua and Afrostyrax (Dehay Theindumentum of hair and also recalls 1957). may consist various types Huaceae. Cavaco (1950) illustrated a Hua-like 2-armed hair, and the peltate scales recall those of Afrostyrax lepidophyllus.

With and Malvaceae arrive Tiliaceae, Bombacaceae, Sterculiaceae, we at a group of

Malvales characterized the of cells cavities and anatomically by presence mucilage or stratified This secondary phloem with triangular broad rays. typically Malvalian character also and but absent from complex is present in Cochlospermaceae Sphaerosepalaceae is

Elaeocarpaceae, Dirachmaceae, and Scytopetalaceae. For Peridiscaceae and Sarcolaenaceae no

data are available. Huaceae differ from the former undisputed Malvalian families in the lack stratification absence of mucilage cells or cavities and also a of the phloem into soft

fibrous The the and portions. dilatation in broad phloem rays is, however, like that in the majority of Malvales.

Tiliaceae are recorded by Metcalfe and Chalk as having anomocytic stomata. The is rather and woodanatomy of the family variable accordingly it is possible to find many the characters also of of Huaceae wood in scattered members of the Tiliaceae a combi-

of and nation broadly banded paratracheal parenchyma, very broad narrow rays has, been encountered the latter however, not in family. The anatomy of the petiole also varies considerably within Tiliaceae but closed vascular cylinders with included medullary bundles as in Huaceae do occur in many representatives (Herlemont). In Bombacaceae the of the and the of scales in several anatomy petiole presence peltate

genera recall Huaceae. The stomata are recorded as predominantly anisocytic (Inamdar and Chohan; Baas, 1972) in the few taxa investigated, but anomocytic and paracytic also in the Catostemma types occur, even same specimens. In they are exclusively paracytic and found cells (Fryns-Claessens Van Cotthem). In Coelostegia I cristarque of the same in of type as Huaceae (Baas, 1972). The wood anatomy Bombacaceae is different from that

in Huaceae because it distri- either shows a storied structure, tile cells, or a parenchyma bution in very narrow lines, or a combination of these characters. The general histology

in Catostemma and to a lesser extent in Scleronema recalls Huaceae, however. Catostemma

wood differs from latter in its the large vessel parenchyma pits, scarcity of narrow rays, and the length of theparenchyma strands (4 cells). In Scleronema not all the parenchyma is bandedbut it is also partly in thin vasicentric sheaths, and the vessel—parenchyma pitting and Bombacaceae seeds those of is large simple. have, as Huaceae, a palisade layer correspon-

ding to the outer epidermis of the inner integument; this layer, however, shows a light

line due to local widening of the lumina. Bombacaceae are eurypalynous but the pollen of

some representatives faintly recalls Huaceae (Fuchs). Though the floral characters, particu-

larly of the ovary, are not suggestive of close affinities of Bombacaceae with Huaceae a substantial of number of characters are shared by some representatives Bombacaceae and

Huaceae (table II) which might indicate a remote phylogenetic relationship.

Malvaceae have many anatomical characters in common withBombacaceae and therefore

provide no new clues in the discussion of affinities of Huaceae. Where Malvaceae deviate from Bombacaceae both floral characters and this in vegetative anatomy, usually concerns

features which indicate that, if related at all, the Malvaceae are more remote from Huaceae

than are Bombacaceae.

mentioned relatives of differ Sterculiaceae, most frequently as possible Huaceae, together

with in the three above mentioned families bark anatomy, presence of mucilaginous

of the from Hua and is elements, and merousness ovary, Afrostyrax. There a noteworthy has exception in Sterculiaceae, however. The ovary of Waltheria is unilocular and two P. Baas: Affinities of Hua and Afrostyrax 189

the lateral ovules of which the lower one is in an almost basal position and develops into have that the only seed (Halle). I suggested (p. 179) unilocular ovary in Huaceae can be and interpreted as a 5-carpellary structure. This would remove objections to linking Hua families Afrostyrax with where the gynoecium is usually 5-merous like Sterculiaceae.

in in Peculiar petals like those Hua occur many Buettnerieae(Leinfellner). The seed anatomy of some commercially important Sterculiaceae is fairly well known (Vaughan, andliterature

cited therein) and the structure of the testa is essentially similar to that of Huaceae (p. 179). of Helicteres also that of- The pollen (Sterc.) is in some respects similar to Huaceae (p. 180).

Stomata of Sterculiaceae are imperfectly known, but are on record as predominantly

in Reevesia. in anisocytic. Paracytic stomata occur, however, Scales as Afrostyrax lepido- Sterculiaceous cells phyllus occur in many taxa. Mucilage and cavities are recorded as of The being absent in some species Sterculiaceae by Solereder (1899 and 1908). petiole

in many Sterculiaceae has a vascular supply which is very similar to that in Huaceae (Dehay,

been 1941). A venation pattern more or less like that of Hua and Afrostyrax has encoun-

tered in Scaphopetalum and slightly less so in Theobroma (p. 180). The wood of Sterculiaceae different from that of because of anatomy most is Huaceae in of the ofthe the occurrence of a storied structure most genera, or presence of tile cells

in the rays. Parenchyma distribution and ray structure are extremely variable within the

and and fall of family, Hua Afrostyrax could within the range variation as far as these

characters Metcalfe and strands of are concerned (Chattaway; Chalk). Parenchyma up cells within Sterculiaceae. has to 8 or more are, however, most uncommon Chattaway

described the structure of the chambered crystalliferous cells in Sterculieae and recorded

the occurrence of extra wall thickenings, similar to those in Huaceae. Lateral vessel wall

also that pitting of Huaceae agrees with in most Sterculiaceae. In conclusion, the wood of well of anatomy Huaceae agrees fairly with that some Sterculiaceae (including Buett-

nerieae) but it has retained more primitive characters like the rudimentary scalariform

perforations in the first formed secondary xylem, the longer vessel members in mature the of such wood, and parenchyma strands more cells. Highly specialized features, as

tile cells and storied structure present in Sterculiaceae but absent from Huaceae, also favour

this conclusion.

of have It is no coincidence that in this part comparisons Huaceae with Sterculiaceae been than other This is in this find more elaborate with any family. because family one can the highest number of characters shared with Huaceae. It shouldbe stressed here, however, members that the characters in common are by no means of constant occurrence in all of

Sterculiaceae and that they are scattered over different representatives of the family. indicate within Hence it is impossible to a group Sterculiaceae to which Huaceae are most closely related.

In table II some selected characters are listed for families which might claim some

affinity on the grounds of the comparisons discussed above. Sterculiaceae rank highest in characters obvious that the number of shared with Huaceae. However, it is Huaceae are

different from this family in anumberofother characters such as its free basal placentation,

absence of mucilage cavities, its unstratified phloem, and the typically longer vessel

members and xylem parenchyma strands. These differences and the fact that no repre-

sentatives of Sterculiaceae could be foundwhere most of the shared characters occurred in

combination, convinced me that Huaceae form a distinct family. The occurrence of some

in cells in other characters, typical for Huaceae, the remaining Malvales, e.g. cristarque

Bombacaceae and Scytopetalaceae, paracytic stomata in Catostemma, ± basal ovules in

Sphaerosepalaceae, theabsenceof mucilage cavities in a Malvalian family like Elaeocarpaceae Malvales s.l. etc. etc., support the inclusion of Hua and Afrostyrax in BLUMEA VOL. XX, No. I, 1972 190

families In comparing Huaceae with a numberof from different orders which suggested themselves because of the occurrence of one or two characters in common (see p. 179 —

with better coincidence of shared features than the families 182) no group was found a also because listed in table II or discussed in the foregoing comparative part. It is of these that I Huaceae the order in of negative reasons propose to keep within Malvales, spite considerable differences that and from each of the separate Hua Afrostyrax its constituent families.

GENERAL CONCLUSIONS

demon- Vegetative anatomy, fruit and seed anatomy, and pollen morphology clearly the strate that Hua and Afrostyrax are closely related genera, definitely belonging to same family. These microscopical character complexes make it also possible to deny relation- ships with Styracaceae and Erythroxylaceae and several other families suggested by different found and authors as close relatives. No family could be with enough micro- macro- morphological characters in common with Hua and Afrostyrax to justify the inclusion

the the of two genera in such a family. Of all plant groups compared, Sterculiaceae show most resemblance with Huaceae. Several unusual characters of Huaceae occur, moreover,

other in some scattered representatives of the Malvales. These resemblances suggest a fairly loose Malvalian affinity. As with the inclusion in this order of other, slightly and aberrant families such as Cochlospermaceae, Sarcolaenaceae, Scytopetalaceae, Sphaerose-

Malvales palaceae, the boundaries of become vaguer through the addition of taxa with conclusion the new characters more typical for other plant groups. A more positive on relationships of Huaceae will not depend on the study of more material of Hua and

of other Afrostyrax but on the availability more comparable data from plant groups of the Dicotyledons.

ACKNOWLEDGEMENTS

R. Metcalfe from Dr. This subject was suggested by Dr. C. (Kew) following an enquiry

R. Melville about the anatomical affinities of Hua. After a preliminary study ofleaf and twig material the former concludedthat the anatomical evidence pointed rather vaguely to unless the an affinity of Hua with Sterculiaceae, although he hesitated to place it there

characters lent from a letter to exomorphic strong support (quoted Dr. Melville, February, information 1968). I am greatly indebted to Dr. Metcalfe for putting this at my disposal.

It is noteworthy that even after much more material has been studied, my rather vague conclusions can hardly be more positive than his tentative suggestion. those institutions Hua and Thanks are due to and persons who provided material of

their slide collections discussions with Afrostyrax or gave access to (see p. 163,183). Helpful

Dr. W. A. van Heel(floral anatomy), Mr. J. Muller (palynology), Dr. N. Parameswaran acknowl- (Hamburg, bark anatomy) and Dr. L. Ruffle(Berlin, leaf venation) are gratefully sectioned of the wood and edged. Miss D. M. Catling, (London) kindly part samples,

carried out the indebted Dr. H. W. L. Ruigrok Halphen reaction. I am particularly to the Mr. J. Isings of the Microscopy Department T.N.O., Delft, for giving access to

Scanning Electron Microscope and to Miss R. Hooftman for operating the instrument. This of Steenis. study was carried out under the supervision Prof. Dr. C. G. G. J. van Thanks for are due to him, Prof. Dr. W. K. H. Karstens, and Mr. H. K. Airy Shaw

critically reading the manuscript. P. Baas: Affinities of Hua and Afrostyrax 191

REFERENCES

P. I. BAAS, 1970. Anatomical contributions to plant taxonomy Floral and vegetative anatomy ofEliaea from

Madagascar and Cratoxylum from Indo-Malesia (Guttiferae). Blumea 18: 369—391.

8: 1972. The vegetative anatomy of Kostermansia malayana Soegeng. Reinwardtia 335 —344. W. TUPPER. Size variations in I. Proc. Amer. Acad. Arts Sci. BAILEY, I. W., & W. 1918. tracheary cells, 54:

149—204. acuminata BANCROFT, H. 1935. Material of Marquesia from Northern Rhodesia. Kew Bull. 10: 559 —568.

of 160. BEIJERSBERGEN, A. 1972. Note on the chemotaxonomy Fluaceae. Blumea 20:

CORNELIUS T. HAMMONDS. Examination BLACKWELL, J.,J. A. & W. 1966. of Theobroma cacao fat for the

of acids. and 1966: presence cyclopropenoid Chemistry Industry 769. E. Mus. BOUREAU, 1958. Contribution a l'etude anatomiquedes especes actuelles de Ropalocarpaceae. Bull.

Nat. Hist. Nat. 30: 213—221.

R. CAPURON, 1962. Revision des Rhopalocarpacees. Adansonia 2: 228—267. Adansonia 1970. Observations sur les Sarcolaenacces. xo: 247—265. A. Sur nouvelle de Sarcolaena vasculaire foliaire. CAVACO, 1950. une cspece (Chlaenaceae) etsur sa structure

Bull. Soc. Bot. Fr. 97: 95—97.

Inst. Sci. 1952. Recherches sur les Chlaenaceae, famille endemique de Madagascar. Mem. Madag. ser.

B, 4: 59—92.

M. M. Trans. 228: CHATTAWAY, 1937. The wood anatomy of the family Sterculiaceae. Philos. Roy. Soc.

313—366.

A. La Huacaceae Rev. Int. Bot. CHEVALIER, 1947. famille des et ses affinites. Appl. Agric. Trop. 27 (No.

291 —292): 26—29.

CRONQUIST, A. 1968. The evolution and classification of flowering plants.

Ann. Nat. DEHAY, CH. 1935. L'Appareil libero-ligneux des Euphorbiacees. Sci. b. ser. 10, 17: 147—290.

Ann. b. 1941. l'Appareil libero-ligneux foliaire des Sterculiacees. Sci. Nat. ser. 11, 2: 45—131. Mem. Sci. 1957. Anatomie comparer- de la feuille des Chlaenacces. Inst. Madag. ser. B, 8: 145—203.

A I. EDLIN, H. L. 1935. critical revision ofcertain taxonomic groups ofthe Malvales New Phytol. 34: 1—20.

ENGLER, A. (ed. H. Melchior) 1964. Syllabus der Pflanzenfamilien, 12th ed. & E. GILG, 1919. Syllabus der Pflanzenfamilien, 7th ed. V. & K. RRAUSE. 1911. Sterculiaceae africanae Bot. Jahrb. 45: 338—339.

ERDTMAN, G. 1952. Pollen morphology and plant taxonomy, Angiosperms.

ETTINGHOUSEN, C. VON. 1858. Ueber die Nervation der Bombaceen. Denkschr. Math. Nat. Classe Kaiserl.

Wiss. Akad. 14. 1861. Die Blatt-Skelette der Dikotyledonen.

FRYNS-CLAESSENS, E., & W. VAN COTTHEM, 1966. Blijft Catostemma een Bombacaceae? Natuurwet.

Tijdschr. 48: 45—50.

FUCHS, H. P. 1967. Pollen morphology of the family Bombacaceae. Rev. Palaeobot. Palyn. 3: 119—132.

R. in X: GERMAIN, 1963. Huaceae, Flore du Congo, du Rwanda et du Burundi 317—319.

1 [ALLI, N. 1961. Sterculiaceae, in Flore du Gabon No. 2.

H. HALLIER, 1923. Beitrage zur Kenntnis der Linaceae. Beih. Bot. Centralblatt 39: 1—178.

HAVEZ, J. M. 1950. l'Appareil libero-ligneux foliaire des Bombacees. Thesis, Lille.

HEGNAUER, R. 1964. Chemotaxonomie der Pflanzen 3: 284—288.

HERLEMONT, R. J. H. 1951. Les Tiliacees d'Indochine. Etude d'anatomie et d'histologie companies de la feuille. Thesis, Lille.

HEINZELMANN, C. E., & R. A. HOWARD, 1948. The comparative morphology of the Icacinaceae V. The

pubescence and the crystals. Amer. J. Bot. 35: 42—52.

Anatomie HUARD, J. 1965. des Rhopalocarpacees. Adansonia 5: 103—123. of 2nd ed. HUTCHINSON, J. 1959. The families flowering plants. CHOHAN. in INAMDAR, J. A., & A.J. 1969. Epidermal structure and stomatal development some Malvaceae

and Bombacaceae. Ann. Bot. (N.S.) 33: 865—878.

Reaktion IVANOV, S. 1927. Die Halphenische aufBaumwollsamenol als allgemeine Reaktion fiir Ole der

Familien Malavaceae, Tiliaceae und Bombacaceae. Ber. Deutsch. Bot. Ges. 45: 588—591. KEATING, R. C. 1968. Comparative morphology of Cochlospermaceae I. Synopsis ofthe familyand wood

anatomy. Phytomorph. 18: 379—392. II. Amer. Bot. 1970. Ibid. Anatomy of the young vegetative shoot. J. 57: 889 —898. IV: KRAUSB, K. 1915. in Engl. & Prantl, Natiirl. Pflanzenfamilien. Nachtrage 201.

LEBACQ, L., & R. DECHAMPS. 1964: Essais d'identification anatomique des bois de l'Afrique Centrale. Kon.

Nr. Mus. Midden Afrika. Ann. IN-8°- Econ. Wetensch. 3. der Kronblatter der Sterculiaceae—Buettnerieae. LEINFELLNER, W. i960. Zur Entwicklungsgeschichte Ost.

Bot. Zeitschr. 107: 153—176. BLUMEA VOL. No. 192 XX, I, 1972

METCALFE, C. R. 1962. Notes on the systematic anatomy of Whittonia and Peridiscus. Kew Bull. 15:

472—475-

& L. CHALK. 1950. Anatomy of the Dicotyledons.

MODBRAED, J. 1913. Ueber die Gattungen Afrostyrax Perk et Gilg und Hua Pierre und die 'Knoblauch-

Rinden' Westafrikas. Bot. Jahrb. 49: 552 —559.

NEDERLANDSE FARMACOPEE, 1966. 6de Uitgave, 2e druk. NETOLITZKY, F. 1926. Anatomie der Angiospermen-Samen. In K. Linsbauer, Handbuch der Pflanzen-

anatomie X.

R. CHATELET. Sur le bois de Africaines. NORMAND, D., & 1955. quarte especes J. d'Agric. Trop. Bot. Appl.

11: 19—27.

O. OLTMANN, 1971. Pollenmorphologisch-systematische Untersuchungen innerhalb der Geraniales. Diss.

Bot. II.

PERKINS, J. 1909. Eine neue Gattung der Styracaceae aus dem tropischen Afrika. Bot. Jahrb. 43: 214—217. 1928. Uebersicht tiber die Gattungen der Styracaceae.

PIERRE, L. 1906. in E. de Wildeman, Flore du Bas- et du Moyen Congo I. Ann. Mus. Congo ser. 5, I: 288.

W. Soc. Bot. ROBYNS, 1958. Le genre Afrostyrax Perk, et Gilg au Congo Beige. Bull. Roy. Belg. 91:

93—98-

N. Y. Contributions the Flora A of Peridiscaceae. SANDWITH, 1962. to of Tropical America 69. new genus

Kew Bull. 15: 467—471. SHAW, PL K. A. 1966. in J. C. Willis, A dictionary of flowering plants and ferns. 7th ed.

SCHNELL, R., G. CUSSET & M. QUENUM. 1963. Contribution I l'etude des glandes extra-florales chez

de Rev. Gen. Bot. quelques groupes plantes tropicales. 70: 269—342.

SOLERBDER, H. 1899 & 1908. Systematische Anatomie der Dicotyledonen (& Erganzungsband). Cuticular Studies aid STACE, C. A. 1965. as an to Plant Taxonomy. Bull. Brit. Mus. (Nat. Hist.) Bot.

4—1: 44.

STEENIS, C. G. G.J. VAN, &R. C. BAKHUIZEN VAN DEN BRINK. 1967. Miscellaneous botanical notes XVI. Bot.

Jahrb. 86: 393. TAKHTAJAN, A. 1969. Flowering plants, origin and dispersal. UPHOF, J. C. TH., K. HUMMEL & K. STABSCHE. 1962. Plant hairs; in W. Zimmermann & P. G. Ozenda,

Handbuch der Pflanzenanatomie, 2nd. ed. IV, 5.

VAUGHAN, J. G. 1970. The structure and utilization of oil seeds.

& R. Les Enc. WALKER, A., SOLANS. 1961. plantes utiles du Gabon. Biol. 56: 203. of the Simarubaceae. WEBBER, I. E. 1936. Systematic anatomy Amer. J. Bot. 23: 577—587. M. ZAHUR, S. 1955. Comparative study of secondary phloem of 423 species of woody Dicotyledons be-

longing to 85 families. Cornell Univ. Agric. Exp. Stn. Mem. 358.

Index to original observations in other families

Irvingiaceae 181, 184

Pandaceae 181

Scytopetalaceae 187 Sphaerosepalaceae 187

Sterculiaceae 180, 189