IAWA Journal, Vol. 15 (2),1994: 161-170

BARK STRUCTURE OF THE SOUTHERN AFRICAN ICACINACEAE

by

M.J. Potgieter and A.E. van Wyk H.G.W.J. Schweickerdt Herbarium, Department of Botany, University of Pretoria, Pretoria, 0002 Republic of South Africa

Summary A description of the bark structure of Theales and later in the Comales. The general southern African species of Apodytes and lack of anatomical information, including bark Cassinopsis is presented for the first time. anatomy, on the Icacinaceae makes compara­ Bark anatomy was found useful in distin­ tive intra- and interfamilial studies extremely guishing between species, especially in the difficult. This could lead to uncertain or incor­ genus Apodytes. Fibres, associated with scle­ rect conclusions. reids, are found exclusively in Apodytes spec. In contrast to the numerous contributions nov. B, whereas A. dimidiata subsp. dimidia­ on wood anatomy of the Icacinaceae by, ta and Apodytes spec. nov. A contain only amongst others, Bailey & Howard (1941), sclereids. Fibres are abundant in Cassinopsis Carlquist (1988), Patel & Bowles (1978), tinifolia, but sparse in C. ilicifolia. Wreathing Gregory (1980), Stott (1927), and Kromhout of the sclerenchyma by calcium oxalate crys­ (1975, 1977), bark anatomy has received little tals occurs in all three species of Apodytes, or no attention. This is especially true of the but not in Cassinopsis. Apodytes contains southern African woody members of the Ica­ prismatic crystals as opposed to druses in Cas­ cinaceae, represented by the genera Apodytes sinopsis. Apodytes dimidiata subsp. dimidiata and Cassinopsis. No information on the bark and Apodytes spec. nov. A show a prismatic anatomy of (hese two genera could be found crystal arrangement, consisting of crystallif­ in the literature. The comprehensive work by erous cells with a large centralised prismatic Roth (1981), which provides a wealth of in­ crystal surrounded by numerous small pe­ formation on bark features in certain families, ripheral crystals. Chambered cystalliferous does not include information on the Icacina­ strands occur in Cassinopsis, but not in ceae. Zahur (1959) supplies limited data on the Apodytes. Bark anatomically Apodytes spec. bark anatomy of Pennantia corymbosa Forst. nov. A shows a closer correlation with A. di­ Anatomical information on the Icacinaceae midiata than with the other species. is needed to clarify this family'S position, and Key words: Icacinaceae, Apodytes, Cassinop­ to enable an extensive comparative study of sis, anatomy, bark. its constituent genera. This paper provides the first description of the bark structure in Introduction Apodytes and Cassinopsis. Two putative new The Icacinaceae have been called a plant Apodytes species, provisionally designated family incertae sedis (Auxiliadora et al. 1991). Apodytes spec. nov. A and Apodytes spec. The delimitation of the family is clear, but its nov. B, are reported for southern Africa. In systematic position is questionable. Today the the present study we have also explored the Icacinaceae are placed in three different or­ diagnostic value of anatomical bark features ders depending on the classification system for distinguishing between these two species. used. According to Cronquist (1981) the fam­ ily belongs to the Celastrales. Dahlgren (1980, Materials and Methods 1983, 1989) removed the Icacinaceae and the Twenty-two bark samples were studied in allied Aquifoliaceae from the Celastrales, and the two southern African genera Apodytes placed them in the Cornales. Thome (1983, and Cassinopsis. Two undescribed Apodytes 1992a, b) first included the Icacinaceae in the species are designated Apodytes spec. nov. A

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Table 1. Members of Icacinaceae studied and voucher specimens. [Specimens are deposited in the H.G.W.J. Schweickerdt Herbarium (PRU).]

Apodytes dimidiata E. Mey. ex Am. subsp. dimidiata: Potgieter 3, 54, 55, 56, 60,62,63; Van Wyk A1046. Apodytes spec. nov. A: Potgieter 66; Van Wyk A1047, 10470. Apodytes spec. nov. B: Van Wyk A1065, A2133, A2134, A12182.

Cassinopsis ilicifolia (Hochst.) Kuntze: Potgieter 2,73,74,165. Cassinopsis timfolia Harv.: Van Wyk 10486, 10487, 10497.

Table 2. Bark anatomical differences between Apodytes and Cassinopsis. (+ =sparse; ++ = moderate; +++ = abundant; - = absent)

Character Apodytes Cassinopsis

Axial phloem parenchyma Tanniniferous cells ++ Crystals + +++ Chambered crystalliferous +++ strands

Phloem rays Tanniniferous cells + Crystals + +++

Sclerenchyma Sclerenchyma type sclereids, sometimes fibres (mainly in C. tinifolia, (in non-dilatating tissue) also with fibres sparse or absent in C. ilicifolia) (Apodytes spec. nov. B) Wreathing of sclerenchyma ++ by crystals

Dilatation tissue Tanniniferous cells +

Crystals Quantity + +++ Axially arranged chambered +++ crystalliferous strand Type prisms druses

Chloroplasts Quantity below periderm + +++

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Table 3. Bark anatomical differences between the southern African species of Apodytes. (+ = sparse; ++ = moderate; +++ = abundant; - = absent)

Character A. dimidiata A. spec. nov. A A. spec. nov. B ------Crystals Type solitary prisms & prisms with 'satellite' crystals solitary prisms

Sclerenchyma (in conducting and non-conducting phloem not affected by dilatation growth) A. dimidiata A. spec. nov. A A. spec. nov. B

Sclerenchyma type sclereids fi bres & sclereids Wreathing by crystals +++ +

Miscellaneous features Slash whitish to pale pale pink to whitish to pale brownish white brownish red brownish white

and Apodytes spec. nov. B (Van Wyk & Pot­ non-collapsed phloem, respectively. Descrip­ gieter 1994). Species names and voucher tions were prepared using the DELTA pro­ specimens for samples studied are listed in gramme (DEscription Language for TAxon­ Table 1. Apodytes dimidiata subsp. dimidiata omy) (Dallwitz 1980) in conjunction with an will henceforth be referred to as Apodytes di­ unpublished list of 97 bark anatomical char­ midiata. acters. For brevity, some descriptions were Bark samples were removed at c. 0.5 m shortened by editing out recurrent passages. height from vertical boles at least 100 mm in diameter, except for the shrubby Apodytes Results spec. nov. B where bark was removed from Intergeneric differences are summarised in stems measuring 50-100 mm in diameter. Table 2, and those between the species of Localities for samples collected are spread Apodytes in Table 3. Anatomical bark descrip­ over the whole distribution range of a species. tions for each of the taxa are supplied below. Samples were preserved in formalin-acetic acid-alcohol (FAA) (Johansen 1940). Apodytes dimidiata (Fig. 1) Anatomical features were studied in trans­ General: Bark surface more or less smooth, verse and radial sections. Standard procedures with bands of horizontally arranged lenticels. were used to prepare 10-15 flm thick sections Rhytidome absent. Bole colour grey-green to from unembedded bark samples on a sliding grey, green pigment visible when bark sur­ microtome. Sections were double stained in face is lightly scraped. Slash whitish to pale safranin 0 and fast-green FCF (Johansen brownish white. Bark width 5-12 mm. 1940) and mounted in Entellan (Art. 7961, Anatomy: Sieve elements abundant, occur­ E. Merck, Darmstadt). Sieve plates were ex­ ring as narrow radial rows between the rays, amined in hand-cut sections of conducting usually obliterated in the non-conducting phlo­ phloem mounted in aniline blue (Eschrich & em; sieve plates strongly oblique; sieve areas Currier 1964) and viewed with fluorescence (12-)13-19(-20) per plate, equally spaced. optics. Drawings of sections were made using Axial phloem parenchyma diffuse between a camera lucida. sieve tube elements, consisting of axially Descriptive terms mainly follow Trocken­ elongated cells; storied structure absent; not brodt (1990). We have used conducting and notably enlarged tanniniferous cells sparse; non-conducting phloem for collapsed and crystals sparse, randomly dispersed.

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.. - . . -.~-, .. .. . _ ...... -, .. - • • I - NP 3

NP

, CP ,

1 4

~ ~ . -=P ~----= . ~~~~...... :.- ..... _C - . C ... ------=­Q- -, .. - - - \ ~ -- NP II •

CP

2 5

Figs. 1-5. Schematic presentation of bark structure, transverse section, sclerenchyma shown in black. - 1: Apodytes dimidiata subsp. dimidiata (Potgieter 54). - 2: A. spec. nov. A (Potgieter 66). - 3: A. spec. nov. B (Van Wyk 12182). - 4: Cassinopsis ilicifolia (Potgieter 2). - 5: C. tinifolia (Van Wyk 10487). - Scale bar = 1 mm; NP = non-conducting phloem; CP =conducting phloem; C =cortex ; P = phellem; PD = phelloderm.

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Phloem rays heterocellular, body ray cells present, composed of sclereids, tending to procumbent with mostly over four rows of up­ be associated with lenticels; crystals absent; right and/or square marginal cells, 1-3-seri­ phelloderm absent or very poorly developed, ate and larger rays commonly 4-10-seriate, stratification absent; tanniniferous cells ab­ 4-12 per mm, the ray height less than 1 mm, sent; crystals absent; green pigment (chloro­ course more or less straight, portion of rays phyll) present; lenticels numerous, arranged traversing or adjacent to sclerenchyma re­ in horizontal rows. maining parenchymatous; ray cells thin-wall­ Cortex persistent, forming a distinct zone ed with prominent pits of different sizes; ag­ in mature bark, parenchymatous, with scat­ gregate rays absent; fusion rays absent; tile tered tanniniferous cells; brachysclereids pres­ cells absent; not notably enlarged tanninifer­ ent. ous cells sparse; crystals sparse. Sclerenchyma present in secondary phlo­ Apodytes spec. nov. A (Figs. 2, 6) em not affected by dilatation growth, compris­ General: Bark surface more or less smooth ing sclereids, arranged as scattered solitary with scattered lenticels. Rhytidome absent. elements or forming small irregular compact Bole colour grey, green pigment visible when groups; sclereids circular, walls more or less bark surface is slightly scraped. Slash pale even, lumen very small, irregularly shaped. pink to brownish red. Bark width 4-6 mm. Dilatation tissue well developed, derived Anatomy: Sieve elements, axial phloem from rays only; rays more or less dilated, parenchyma, phloem rays, sclerenchyma, cal­ wedge-shaped; well-defined dilatation meri­ cium oxalate crystals, secretory structures and stem(s) absent; secondary sclerenchyma pres­ cortex as in A. dimidiata. ent; sclereids more or less circular to irregular Dilatation tissue well developed, derived in outline, irregularly dispersed as clusters, from rays only, rays more or less dilated, mainly associated with aggregates of primary wedge-shaped; well-defined dilatation meri­ sclerenchyma; sclerenchyma ring (remnants stem(s) absent; secondary scIerenchyma pres­ of primary phloem fibres) present, well devel­ ent; sclereids circular to irregular in shape, oped; not notably enlarged tanniniferous cells arranged in discontinuous tangential bands in sparse; crystals sparse. older dilatation tissue, or irregularly dispersed Calcium oxalate crystals prismatic, sparse, as clusters; sclerenchyma ring (with primary sometimes with small peripheral crystals sur­ phloem fibres) present, well developed; not rounding the main crystal, mainly in ray cells, notably enlarged tanniniferous cells sparse; rarely in axial phloem parenchyma; crystaIIif­ crystals sparse. erous cells wreathing the sclerenchyma, not Mature periderm one to three, 0.3-1 mm encased in sclerotic elements; axially arrang­ thick, ramified (net-like), the course straight, ed chambered crystaIIiferous strands absent. cream-coloured; phellem compact, lignified Secretory structures absent; not notably cells (phellem/phelloid) present, stratification enlarged tanniniferous cells sparse, mainly in present or absent, layers of lignified cells alter­ rays and phloem parenchyma, also in dilata­ nating with non-lignified ones, lignified cells tion tissue. Starch present, sparse to abundant; (phellem/phelloid) with tangential diameter grains spheroidal. greater than radial diameter, cell walls thicken­ Mature periderm one, 0.5 mm thick, course ed, U-shaped, with clear cell lumen; idioblasts straight, cream-coloured; phellem compact absent; crystals absent; phelloderm either ab­ and squashed, lignified cells (phellem/phel­ sent or poorly developed, or present and well loid) present, stratification absent, cells usu­ developed, stratification absent, parenchyma­ ally with tangential diameter greater than tous, parenchyma cells mainly with tangential radial diameter, either with all walls evenly diameter greater than radial diameter; scIereids thickened, or only inner tangential walls thick­ present, spheroidal; tanniniferous cells sparse ened, U-shaped in cross section with obscure or absent; crystals abundant to sparse or ab­ cell lumen; conspicuously radially enlarged sent; green pigment (chlorophyll) present; phellem cells absent; idioblasts occasionally lenticels numerous.

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Figs. 6 & 7. Crystalliferous tissue. - 6: Apodytes spec. nov. A (Van Wyk 10470), prismatic crystal with 'satellite' crystals in dilatation tissue; scale bar = I ~m. - 7: Cassinopsis ilieifolia (Potgieter 165), chambered crystalliferous strands containing druses in non-conducting phloem; scale bar = 10 )lm.

Apodyces spec. nov. B (Fig. 3) and crystalliferous cells wreathing the scle­ General: Bark surface smooth with scatter­ renchyma, not encased in sclerotic elements; ed lenticels. Rhytidome absent. Bole colour axially arranged chambered crystalliferous pale grey. Slash whitish to pale brownish strands absent. white. Bark width 0.5-9 mm. Mature periderm one, course straight, Anatomy: Sieve elements, axial phloem cream-coloured; phellem compact, lignified parenchyma, phloem rays, dilatation tissue, cells (phelleml phelloid) present, stratification secretory structures and cortex as in A. dimi­ absent, phellem without clearly discernible diata. cells; idioblasts absent; crystals absent; phello­ Sclerenchyma present in secondary phloem derm absent or very poorly developed; green not affected by dilatation growth, comprising pigment (chlorophyll) present. fibres and sclereids, arranged as scattered soli­ tary elements or forming small irregular com­ Cassinopsis Weifolia (Figs. 4, 7) pact groups; fibres with walls very thick, General: Bark surface smooth. Rhytidome occasionally with a few remaining cellulosic absent. Bole grey, green pigment visible when (unlignified); sclereids circular to irregularly the bark surface is lightly scraped. Slash pale shaped, walls more or less even, lumen small cream or whitish. Bark width 3- 5 mm. and round, as well as large and irregular. Anatomy: Sieve elements abundant, oc­ Calcium oxalate crystals prismatic, sparse, curring as narrow radial rows between the located mainly in axial phloem parenchyma rays, usually obliterated in the non-conducting

Downloaded from Brill.com10/03/2021 01:44:29PM via free access Potgieter & Van Wyk - Bark structure in Icacinaceae 167 phloem; sieve plates strongly oblique; sieve with tangential diameter mostly greater than areas 12-20 per plate, equally spaced. radial diameter, walls evenly thickened; tan­ Axial phloem parenchyma diffuse between niniferous cells absent; crystals abundant or sieve tube elements, consisting of axially elon­ absent; green pigment (chlorophyll) present; gated cells; storied structure absent; tanninif­ lenticels numerous. erous cells absent; crystals usually abundant; Cortex present, forming a distinct zone chambered crystalliferous strands present. in mature bark, parenchymatous, brachyscle­ Phloem rays heterocellular (type 1), 1-3- reids present. seriate, larger rays commonly 4-1O-seriate, 4-12 per mm, ray height less than 1 mm, Cassinopsis tinifolia (Fig. 5) course more or less straight, portion of rays General: Bark surface smooth. Rhytidome traversing or adjacent to sclerenchyma remain­ absent. Bole colour pale grey to greenish ing parenchymatous; ray cells thin-walled, grey, green pigment visible when outer bark pitted; aggregate rays, fusion rays, tile cells, is lightly scraped. Slash whitish. Bark width and tanniniferous cells absent, crystals abun­ 4.5-5 mm. dant. Anatomy: Sieve elements, axial phloem pa­ Sclerenchyma sparsely present or absent renchyma, phloem rays, calcium oxalate crys­ in secondary phloem not affected by dilatation tals, secretory structures and cortex as in C. growth, comprising fibres, absent or sparsely ilicifolia. present in secondary phloem affected by dila­ Sclerenchyma present in secondary phloem tation growth, arranged as scattered solitary not affected by dilatation growth, comprising elements or small aggregates of 2 or 3 cells, fibres, abundant, predominantly solitary or in walls very thick. small clusters of 2-4 cells, often arranged in Dilatation tissue well developed, derived radial rows (seen in transverse section); fibres from rays only; rays regularly dilated, wedge­ non-septate, walls very thick. shaped; well-defined dilatation meristem(s) Dilatation tissue well developed, derived absent; secondary sclerenchyma present; scle­ from rays only; rays regularly dilated, wedge­ reids circular, irregularly dispersed as clus­ shaped; well-defined dilatation meristem(s) ters; sclerenchyma ring (with primary phloem absent; secondary sclerenchyma present or fibres) present, poorly to well developed; tan­ absent; sclerenchyma ring (with primary phlo­ niniferous cells absent; crystals abundant, ran­ em fibres) present, well developed; tanninifer­ domly distributed. ous cells absent; crystals abundant to sparse, Calcium oxalate crystals abundant, druses, randomly distributed. mainly in axial phloem parenchyma and ray Mature periderm one, course straight and cells, less frequent in the dilatation tissue, not cream-coloured; phellem compact, lignified encased in sclerotic elements; axially arranged cells (phellem!phelloid) present (not clearly chambered crystalliferous strands present. discernible, a homogeneous matrix); lenticels Secretory structures, including tanninifer­ not observed; otherwise as in C. ilicifolia. ous cells, absent. Starch present, abundant; grains spheroidal. Discussion Mature periderm one to three, 0.4-0.7 mm The investigated species conform to the thick, ramified (net-like) where two or three general bark anatomical pattern for the par­ periderms are present, course straight, cream­ ticular genus to a great degree (Table 2). Inter­ coloured; phellem compact (cells not clearly specific structural differences do, however, discernible), lignified cells (phellem! phelloid) occur in both Apodytes (Table 3) and Cassi­ present, stratification absent, cells usually nopsis. There is a closer correlation concern­ with the tangential diameter greater than the ing bark anatomical characters between Apo­ radial diameter, conspicuously radially en­ dytes dimidiata and Apodytes spec. nov. A, larged phellem cells absent, all walls evenly than between these two species and Apodytes thickened; idioblasts absent; crystals absent; spec. nov. B. Additional notes and discussion phelloderm absent or very poorly developed, on bark anatomical features of different tissue stratification absent, parenchymatous, cells types!structures are supplied below.

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Sieve elements This contrasted sharply with Apodytes spec. The sieve elements discernible in the con­ nov. B which has fibres associated with scle­ ducting phloem, are more or less similar in reids. Although fibres are present in both spe­ the different species. Although the number of cies of Cassinopsis, C. ilicifolia usually lacks sieve areas per plate varies from sample to fibres in the secondary phloem and may con­ sample, this variation is not taxonomically tain only a few primary phloem fibres in the significant. Pennantia corymbosa Forst., clas­ sclerenchyma ring ('pericycle') separating the sified in the same tribe (Icacineae) as Cassi­ dilatating phloem and cortex. Fibres are ran­ nopsis and Apodytes, displays the same type domly scattered as solitary elements, or ar­ of sieve tube, namely type I (Zahur 1959). ranged in small irregular compact groups. Wreathing of the sclerenchyma by crystals Axial phloem parenchyma has been observed in Apodytes, although it is Axial phloem parenchyma arrangement is less marked in Apodytes spec. nov. B than in fairly similar in all the species, with the cells the other two species. In Cassinopsis wreath­ diffuse between the sieve tube elements. Pa­ ing of sclerenchyma is absent in all the exam­ renchyma cell expansion, mainly in the tan­ ined samples. gential plane, is pronounced in the non-con­ ducting phloem, with cells becoming more Dilatation tissue isodiametric towards the dilatation tissue when Phloem rays tend to be weakly and irreg­ viewed in radial longitudinal section. ularly dilated in Apodytes, whereas those in In Apodytes tanniniferous cells are usually Cassinopsis are regularly dilated. A well de­ conspicuous, though sparse, but in Cassi­ veloped sclerenchyma ring has been found in nopsis nearly or totally absent. Calcium ox­ all the investigated taxa. Persistent primary alate crystals are very sparse in Apodytes and phloem caps associated with this ring can still not arranged in chambered crystalliferous be distinguished in some bark samples. Hence strands as in Cassinopsis. we conclude that the sclerenchyma ring de­ marcates the secondary phloem and cortex. Phloem rays Randomly dispersed prismatic crystals (Apo­ Ray construction is fairly uniform in the dytes) and druse crystals (Cassinopsis) ap­ species examined, and of limited diagnostic pear, sparsely (Apodytes) or abundantly (Cas­ importance. Ray structure is heterocellular, sinopsis), in the dilatation tissue. Tanninifer­ with the procumbent portion usually 1-3-seri­ ous cells are sparse to abundant in Apodytes, ate; larger rays are 4-10-seriate. The rays are but absent in Cassinopsis. In some samples composed only of thin-walled, non-lignified of Cassinopsis tinifolia fibres are arranged in cells which are either occasionally tanninifer­ radial rows (as seen in transverse section). ous (Apodytes) or non-tanniniferous (Cassi­ nopsis). Cells do not become sclerosed when Calcium oxalate crystals traversing sclerenchymatous elements. Ray Apodytes dimidiata and Apodytes spec. course is usually straight. Crystals are sparse nov. A show a peculiar type of crystalliferous (Apodytes) or abundant (Cassinopsis). Tile cell, consisting of a central prismatic crystal cells and aggregate rays are absent. surrounded by several small peripheral pris­ matic crystals. This is considered a good Sclerenchyma taxonomic character for distinguishing A. di­ Sclerenchymatous elements are considered midiata and Apodytes spec. nov. A from Apo­ the most significant pattern-producing element dytes spec. nov. B. This type of crystal ar­ in the bark. Although some intraspecific varia­ rangement has also been noted by Baas (1975) tion in form and distribution has been found in Sphenostemon (Sphenostemonaceae), in between bark samples, this tissue is diagnos­ which the crystals are styloids. tically valuable in the investigated material. The most obvious diagnostic difference In secondary phloem not affected by dila­ between the bark of Apodytes and Cassinop­ tation growth, only sclereids have been found sis is the presence of druses in Cassinopsis, in A. dimidiata and Apodytes spec. nov. A. and prisms in Apodytes. Moreover, druses

Downloaded from Brill.com10/03/2021 01:44:29PM via free access Potgieter & Van Wyk - Bark structure in Icacinaceae 169 in Cassinopsis are present in long, axial­ (some taxa only). Unlike some Aquifoliaceae, ly arranged, chambered strands, distributed the investigated Icacinaceae do not have crys­ throughout the secondary phloem and even tals encased in sclereids. However, because persisting in the dilatation zone. Chambered of the limited number of taxa studied, the in­ crystal strands - solitary and irregularly dis­ formation at hand is insufficient to draw any persed, or in groups - are a good diagnostic definitive conclusions. feature for fibre identification. True fibres, un­ This study has shown that bark ana­ like elongated sclereids, are often associated tomical features are useful for elucidating with chambered crystalliferous strands. taxonomic relationships between the southern African species of Apodytes and Cassinop­ Mature periderm sis. On the generic level, crystal type and the No clearly discernible differences in the presence or absence of tanniniferous cells have periderm have been observed between spe­ proved to be the most useful distinguishing cies of Apodytes and species of Cassinopsis. characters. Minor distinctions between Apodytes and The diversity encountered in the bark struc­ Cassinopsis include lenticels which tend to ture of Apodytes provides further support for be arranged in horizontal rows in Apodytes the proposed establishment of the two new dimidiata, but randomly in the other species. Apodytes species. Apodytes dimidiata and In the southern African species of Icacina­ Apodytes spec. nov. A are characterized by ceae, the periderm does not provide many prisms with 'satellite' crystals and sclereids, diagnostic characters. and Apodytes spec. nov. B is distinguished by solitary prisms and fibres (in addition to Cortex sclercids ). A persistent cortex is present in all the in­ Distinguishing characters between the two vestigated species. Crystal types are the same investigated species of Cassinopsis are not as those in the conducting and non-conducting very marked. Both conform to the generic bark phloem. Except for the presence of tanninifer­ structure by the presence of an abundance of ous cells in Apodytes, it provides no signifi­ druse crystals in chambered crystalliferous cant interspecific diagnostic characters. strands and an absence of tanniniferous cells. Sclerenchyma is very sparse, or even absent, Taxonomic conclusions in the conducting and non-conducting phloem Various estimates put the number of spe­ of C. ilicifolia, whereas fibres are common in cies in Icacinaceae between 380 and 400. Prior C. tinifolia. to the present study, bark anatomical informa­ Further bark anatomical studies on the es­ tion was available for only one species, Pen­ timated 15 species of Apodytes recognized at nantia corymbosa (Zahur 1959). This lack of one time or another and lumped mostly under information makes comparative bark anatom­ A. dimidiata by Sleumer (1976), would be ical work on the family very difficult, if not informative. To evaluate the significance of impossible. The present study should be seen bark anatomical characters in Cassinopsis as a starting point for such studies on the Ica­ more fully, the four Malagasy species should cinaceae. Taxonomic conclusions at higher also be investigated. This would determine the levels of classification will be possible only consistency and therefore the taxonomic value after more studies on other icacinaceous gen­ of characters at the generic and specific levels. era. Baas (1975) provides limited information on the bark of members of putative related families, e. g. !lex (Aquifoliaceae), Oncothe­ Acknowledgements ca (Oncothecaceae), Phelline (Phellinaceae), The authors express their appreciation to and Sphenostemon (Sphenostemonaceae). Ms. M. Mossmer for critically reading and Similarities between the bark of Icacinaceae improving the manuscript. This research was and that of Aquifoliaceae include the presence supported in part by research grants from the of a perivascular sclerenchyma ring, prismatic Foundation for Research Development and crystals, brachysclereids and the lack of fibres the University of Pretoria.

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References Kromhout, C. P. 1975. 'n Sleutel vir die mi­ Auxiliadora, M., C. Kaplan, J. Ribeiro & kroskopiese uitkenning van die vernaam­ O.R. Gottlieb. 1991. Chemogeographical ste inheemse houtsoorte van Suid-Mrika. evolution of terpenoids in Icacinaceae. Bull. 50, Dept. of Forestry, Pretoria. Phytochem. 30: 2671-2676. Kromhout, C. P. 1977. 'n Studie van die hout­ Baas, P. 1975. Vegetative anatomy and the anatomie van die vernaamste houtsoorte affinities of Aquifoliaceae, Sphenostemon, van Suid-Afrika en 'n sleutel vir hul mikro­ Phelline, and Oncotheca. Blumea 22: 311- skopiese uitkenning. Ph.D. Thesis, Uni­ 407. versity of Stellenbosch. Bailey, I.W. & R.AHoward. 1941. The com­ Patel, R.N. & A Bowles. 1978. Wood anato­ parative morphology of the Icacinaceae. my of the dicotyledons to New Zealand. 1. Arnold Arbor. 22: 125-132; 171-187; 12. Icacinaceae. N. Z. J. Bot. 16: 7-12. 432-442; 556-568. Roth, I. 1981. Structural patterns of tropical Carlquist, S. 1988. Comparative wood anat­ barks. In: Handbuch der Pflanzenana­ omy. Systematic, ecological, and evoluti­ tomie. IX/3. Gebr. Borntraeger, Berlin. onary aspects of dicotyledon wood. Sprin­ Sleumer, H. 1976. Icacinaceae. In: Flora Ma­ ger-Verlag, Berlin, Heidelberg. lesiana I, 7: 1-87. Wolters-NoordhofPub­ Cronquist, A 1981. An integrated system of lishing Co., Groningen. classification of flowering plants. Colum­ Stott, M.H. 1927. Notes on the characteris­ bia University Press, New York. tics and minute structure of thirty woods indigenous to South Africa. S. Afr. 1. Sci. Dahlgren, G. 1989. The last Dahlgrenogram: 24: 298-317. System of classification of the dicotyle­ Thome, R.F. 1983. Proposed new realign­ dons. In: K.Tan (ed.), The Davis and Hedge ments in the angiosperms. Nordic J. Bot. Festschrift: 237-248. Edinburgh Univer­ 3: 85-117. sity Press, Edinburgh. Thome, R.F. 1992a. An updated phyloge­ Dahlgren, R. 1980. A revised system of clas­ netic classification of the flowering plants. sification of the angiosperms. 1. Linn. Aliso 13: 365-389. Soc., Bot. 80: 91-124. Thome, R.F. 1992b. Classification and geo­ Dahlgren, R. 1983. General aspects of angio­ graphy of the flowering plants. Bot. Rev. sperm evolution and macrosystematics. 58: 225-348. Nord. J. Bot. 3: 119-149. Trockenbrodt, M. 1990. Survey and discus­ DaIIwitz, M.J. 1980. User's guide to the sion of the terminology used in bark anat­ DELTA system: a general system for en­ omy. IAWA Bull. n.s. II: 141-166. coding taxonomic descriptions. Available Van Wyk, AE. & M.J. Potgieter. 1994. Two from the author free of charge. CSIRO Di­ new species of Apodytes (Icacinaceae) vision of Entomology, Canberra. from southern Africa. S. Afr. J. Bot. 60 Eschrich, W. & H.B. Currier. 1964. Identifi­ (in press). cation of callose by its diachrome and flu­ Wood, G.H.S. 1952. Bark as a means of orochrome reactions. Stain Technol. 39: tree identification. Univ. Oxford Forestry 303-307. Soc. 1. 6: 15-27. Gregory, M. 1980. Wood identification: an Zahur, M. S. 1959. Comparative study of sec­ annotated bibliography. lAW A Bull. n.s. ondary phloem of 423 species of woody I: 3-41. dicotyledons belonging to 85 families. Johansen, D.E. 1940. Plant microtechnique. Cornell Univ. Agric. Exp. Sta. Mem. 358: McGraw-Hill Book Co. Inc., New York. 1-160.

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