Grana 24: 23-3 1, 1985 Pollen ultrastructure of the Philydraceae

MICHAEL G. SIhlPSON

Simpson, M. G. 1985. Pollen ultrastructure of the Philydraceae. - Grana 24: 23-31, 1985. Uppsala 8 May 1985. ISSN 0017-3134. Pollen morphology, sculpturing, and wll ultrastructure of the five species in the monocot family Philydraceae were investigated in order to assess phylogenetic relationships. All members of the Philydraceae have monosulcate, heteropolar pollen grains with a tectate- columellate exine having distinctive lamellae inner to the foot-layer. Histochemical tests of Pliilpdrrim lanirgiriosrirn indicate an ektexinous exine composition. The aperture uall of all members of the family consists of a thick, 2-layered intine with exine absent or composed of scattered deposits. The inner intine layer is infused with numerous vesicular or channel- like structures. Histochemical tests of Philpdriirn laniiginosirrri suggest that the outer intine layer is primarily cellulosic and the inner intine layer is pectic-rich, a trend opposite from that noted in pollen of other monocot taxa. Palynological similarities between the Philydra- ceae and related families, including monosulcate apertures and a tectate-columellate exine, are hypothesized to represent ancestral features which are of no value in assessing phylogenetic relationships. hficlinel G. Simpson, Depnrfrtient of Bornrip, Dirke Uiiiversirp, Dirrhnrn, Norzh Cnrolinn 27706, USA (Current address: Depnrttnent of Biology, Albrighr College, Rending, Penn- sylvonia 19603, USA) (hfanuscript receiwd 2 September 1983. revised version accepted 7 hinrch 1981)

The Philydraceae (sensu Hamann 1966) are a small to either the Haemodoraceae or Pontederiaceae. monocot family of four genera and five species: For example, Engler & Prantl (1930) placed the Helriilioltzio (2 species; eastern Australia, New Philydraceae adjacent to the Pontederiineae (Ponte- Guinea). Orrhorhjl~x(monotypic; eastern Austra- deriaceae and Cyanastraceae), whereas Hutchinson lia); Pliilydrella (monotypic; western Australia), (1934, 1959, 1973) classified the Philydraceae with and Philydririn (monotypic; Australia, Malaysia, five other families (Taccaceae, Apostasiaceae, Vel- and eastern Asia). All family members are peren- loziaceae, Hypoxidaceae, and Haemodoraceae) in nial, rhizomatous or cormose herbs having disti- his order Haemodorales. Hamann (1966) suggested chous, ensiform (equitant, unifacial) leaves and a close affinities between the Philydraceae and Pon- simple to branched spicate, bracteate inflores- tederiaceae and possibly also to the Haemodora- cence. The Philydraceae probably constitute a ceae and Hypoxidaceae. The Philydraceae was monophyletic taxon as evidenced by the occur- classified by Dahlgren (1980) and Dahlgren & Clif- rence of a distinctive and apparently derived floral ford (1982) as the order Philydrales, closely related Downloaded by [SDSU San Diego State University] at 10:35 25 February 2015 structure, consisting of: fusion of the two outer to the Haemodorales, Pontederiales, Velloziales, latero-posterior tepals with the inner posterior tepal and . Thorne (1976) grouped the Phi- and presence of a single, anteriorly positioned sta- lydraceae with the Pontederiaceae in the suborder men (Hutchinson 1973, Hamann 1966). Pontederiineae (Commeliniflorae), to which Thorne Because of the morphological homogeneity of the (1981), based on chemical evidence (Hams & Hart- Philydraceae, taxonomists have encountered few ley 1980) added the Haemodoraceae. The Philydra- differences as to the circumscription and intrafamil- ceae were thought to share common ancestry with ial classification of the family (see Hamann 1966). the Pontederiaceae by Takhtajan (1980) because of Interfamilial classifications of the Philydraceae similarities in anatomy and embryology. Finally, have varied; most systems place the family "near" Cronquist (1981) placed the Philydraceae adjacent

Griina 24 24 M. G. Sitlipsoti Downloaded by [SDSU San Diego State University] at 10:35 25 February 2015

Fig. 1. Heltnholrziu. A-E: If. acorvolio. (A) Whole grain, Apertunl wall, showing thick, 2-layered intine (11 with aperture above. SEM ~2700.(B) Close-up; note reticu- numerous vesicles (arrow) of inner intine layer. Note late non-apertunl \mil and verrucate apertunl elements. exine (e) composed of a continuous thin layer and larger SEM XS 100. (C) Interface between apertural wall (lower irregular exine elements. ~20000.(E) Nonapertural wall. left) and non-apertural wall; note, in apertural region, Note 2-layered intine (9, with vesicular inner layer, and expansion of the 2-layered intine. TEM X 11 0oO. (D) tectate-colurnellate exine (e), with lamellate inner foot-

Grana 24 Exine iiltrastriictiire of Philydraceae 25

to the Pontederiaceae and Haemodoraceae in the pollen morphology and wall ultrastructure. A tec- . tate-columellate exine wall architecture is found in All four genera and five species of the family investigated members of the Cyanastraceae (Cyan- have been investigated palynologically with bright- astrrim), Hypoxidaceae (Hypoxis, Curculigo), Pon- field microscopy (Erdtman 1966, Hamann 1966 and tederiaceae (flereranthera, Pontederia), Taccaceae references cited therein). Pollen grains of Phily- (Tacca), and Velloziaceae (Barbecmia, Vellozia). drum are distinct in the family in being united as In contrast, fourteen genera of the Haemodoraceae tetragonal tetrads at maturity; grains of the other have a 1- to 3-layered, non-tectate-columellate ex- four species are shed as monads (Erdtman 1966, ine architecture (see Simpson, 1983a). Therefore, a Hamann 1966). Erdtman (1966) described Orrhothy- primary goal of the present study is to determine lax glaberrima, pygmaea, and Phily- what similarities and differences of pollen sculptur- drum laniiginosirm as monosulcate; Ilelmholrzia ing or wall architecture occur between members of acorifolia was described by Erdtman as “probably the Philydraceae and these presumed related fam- 3-Or zonisulcate.” Hamann (1966), however, disa- ilies. In addition, the determination of whether greed with Erdtman, and described both H. acori- these palynological features are ancestral or de- folia and H. nouo-griineensis as monosulcate. (Ha- rived within this complex of families is vital in mann reported that the “3-sulculate” condition de- order to assess their value in recognizing monophy- scribed by Erdtman was possibly the result of a letic taxa (sensu Hennig 1966). shrinkage effect from acetolysis.) With regard to sculpturing, Erdtman (1966) described Orrhothylux MATERIAL AND METHODS and Philydrella as “reticulate (polybrochate),” and Philydriim as “reticulate (slightly heterobrochate; Pollen samples were obtained either from herbarium sheets (“DRIED”) or were fixed in formalidacetic ac- muri +I- duplibaculate).” Both species of Helm- idalcohol (“FAA”). Dried anthers were re-hydrated in holtzia are reported to have a tine, unresolvable Aerosol OT for 1-4 days, followed by several water (with light microscopy) exine sculpturing (Hamann rinses. The following species were examined (parentheses 1966). The sexine of all genera in the family is indicate herbaria where vouchers are deposited): Helm- holrziu acorifoliu F. v. Mueller ‘‘FAA’’ - M. G.Simpson described as thicker than or as thick as the nexine 81-16A (DUKE); H. now-girineensis(Krause) Skottsberg (Erdtman 1966). Erdtman summarizes the Philydra- “DRIED” - L. J. Brass 12859 (A); Ortho1hylaxgloberri- ceae as “pollenomorphologically a +/- heteroge- miis (Hooker fil.) Skottsberg “FAA” - cult. Hod. Bot. nous family.” Kew (Herb. U. Hamann, Bochum 1183); Philydrellu pyg- The purpose of the present study is to describe moea (R. Brown) Caruel “FAA” - M. G. Simpson 28IX81A (DUKE); Pbilydrum lunirginosum Banks & So- and characterize, using SEM and TEM, the pollen lander ex Gaertner “FAA” - E. F. Constable 4128 sculpturing and ultrastructure of the Philydraceae in (Herb. U. Hamann, Bochum 959, ex. Herb. NSW 58993). order to assess phylogenetic relationships of the fa- For SEM studies, whole, dehisced anthers containing mily, particularly with reference to other monocoty- mature pollen were placed in a modified capsule between two 5 pm Nucleopore filters. Anthers or free pollen were ledonous taxa. Of the families cited by the above progressively dehydrated to 100% ethanol, then infiltrat- authors to be closely related to the Philydraceae, ed with 100% Freon I13 (intermediate fluid). The material the Cyanastraceae (Simpson, in press, Haemo- was critical-point dried in a BOMAR SPC W/EX drier doraceae (Simpson 1983 a), Velloziaceae (Ayensu using COz as the transition fluid. Pollen grains were & tapped onto a stub covered by double-stick Scotch tape, Skvarla 1974), and selected members of the Hy- sputter coated (ca. 200 A thickness) with goldpalladium poxidaceae, Pontederiaceae and Taccaceae (Simp- (60/40),and viewed with a Jeol TZO SEM. Downloaded by [SDSU San Diego State University] at 10:35 25 February 2015 son 19836) have been investigated with respect to For TEM analysis of wall architecture, pollen samples were fixed in 4.2% buffered gluteraldehyde for 2 hours, rinsed in 0.1 M Sorensen’s phosphate buffer, and post- layer (arrow). TEM X21 OOO. F-J: 11. now-guineensis.(0 fixed in 2% Os04for 1 hour, After two rapid hater rinses Whole grain, sulcate aperture above. SEM x3 100. (G) and progressive dehydration to 100% ethanol, the materi- Close-up, nonapertural wall. SEM ~4700.(H) Close-up, al was infiltrated in a series of increasing concentrations edge of apertural uall (a). SEM X4600. (I) Apertural of Spurr’s resin (Spurr 1%9). Fully infiltrated grains were interface, aperture region to right. Note exine deposits (e) placed in an obconical BEAM capsule and polymerized and thick, 2-layered intine (17, with vesicular inner layer %I2 hours in a 65 C oven. Sections ca. 500400 A thick (arrow). TEM ~16000.(J) Non-apertural wall, showing were prepared using a Dupont diamond knife on a Cam- tectate-columellate exine with prominent lamellae (arrow) bridge-Huxley ultramicrotome, and mounted on uncoated at inner foot-layer. TEM x34000. 200 mesh copper grids. Preparations were post-stained

Grana 24 26 M. G. Siriipsori

Fig. 2. Orrhorhylax glaberrirnus (A) Whole grain, aperture Note exine (e) and thick, 2-layered intine (i) of aperture, above. SEM x3500. (B) Close-up of non-apertural (left) with obscure channels of inner layer (arrow). TEM and apertural (right) walls. SEM ~7000.(C) Grain cross- x IOOOO. (E) Non-apertural wall with tectate-columellate section. Note aperture (a). TEM ~4200.(D) Interface exine, having lamellate inner foot-layer (arrow). TEM between apertural )

with uranyl acetate (saturated in 95% ethanol, IS minutes) Mean maximum pollen lengths (preceeding pollen de- and lead citrate (0.2% aq., 7 min) and viewed with a scriptions) were measured from fixed or rehydrated grains Siemens Elmiskop 101 TEM. mounted in 70% ethanol. Pollen terminology follows that For cytochemical tests unacetolyzed, FAA-fixed pollen of Walker & Doyle (1975). grains were stained, mounted whole in glycerol, and pho- tographed in optical cross-section with brightfield or UV fluorescence microscopy, using a Leitz Laborlux com- pound microscope (see Kress & Stone 1982, for a review R ES U LTS of pollen cytochemistry methods). Pectic-rich intine bas Downloaded by [SDSU San Diego State University] at 10:35 25 February 2015 ULTRASTRUCTURE detected by positive staining with alcian blue (I % in 3% POLLEN acetic acid, 5 min). Intine containing polysaccharides with Iielriiholtzia (2 of 2 species investigated) I ,2-glycol groups (presumed to be predominantly cellulo- 11. acorifolia. -Grains 26 pm, monosulcate, heter- sic) aas identified by red staining using the periodic acid- opolar (Fig. 1 A). Sculpturing of non-apertural wall Schiff (PAS) reagent (after Jensen 1%2). Ektexine \bas identified by bright red staining with basic fuchsin (I % in reticulate, apertural surface with scattered verru- 95% ethanol, 5 rnin) and by bright yellow fluorescence cose or irregular elements (Fig. 1 B). Non-apertural with auramine 0 (0.01 % in O.05M tris-HCI buffer, pH 7.2, initine 2-layered, with vesicles in the inner layer 5 min). Fluorescence illumination was achieved with an (Fig. 1 E). Apertural intine thick, 2-layered (Fig. Osram HBO 200 watt super pressure Hg lamp; filters used were aBG-38 heat filter, UG-I UV excitation filler, BG-23 1 C, D) with numerous contorted, vesiculare struc- red suppression filter, and a blue or UV barrier filter. tures comprising the inner layer (Fig. 1D). Non-

Grana 24 Exirie iiltrnstriictiire of Philydrnceae 27

Fig. 3. Philydrella pygmaea. (A) Whole grain, aperture x 11501). (E) Non-apetural wall. Note 2-layered intine (11, above. SEM x2400. (B) Close-up of nonapertural (left) with vesicular inner layer, and tectate-columellate exine and apertural (right) malls. SEM ~8 100. (C) Interface (e) with lamellate inner foot-layer (arrow). TEM X22400. between apertural wall (left) and nonapertural mall (right). (F) Apertural mall. Note outer exine layer (e) and thick, 2- Note thick, 2-layered intine 0.TEM x5600. (D)Whole layered intine (i), with vesicles (arrow) in inner layer. grain cross-section, showing aperture (upper left). TEM TEM x 17800.

apertural exine tectate-columellate (semi-tectate), Orrhorliylnx (monotypic) with a continuous, homogeneous foot-layer; lamel- 0. glnberrimiis. - Grains 22 pm, monosulcate, late, apparently ektexinous deposits present at in- heteropolar (Fig. 2A, C). Non-apertural wall foveo- ner foot-layer (Fig. 1 E). Exine of aperture region late to finely reticulate; apertural region with a few composed of scattered, irregular, apparently ektex- scattered, irregular exine elements (Fig. 2A, B). inous elements atop a thin, continuous nexine of Intine of non-apertural and apertural regions faintly uncertain composition (Fig. 1 C, D). 2-layered (Fig. 2 D), with obscure channel-like 11. now-giiineensis. - Grains 25 pm, rnonosul- structures present in the inner apertural intine (Fig. cate, heteropolar (Fig. 1 F). Non-apertural wall re- 2 D). Non-apertural exine tectate-columellate, ap- Downloaded by [SDSU San Diego State University] at 10:35 25 February 2015 ticulate (Fig. I G), apertural wall obscure in materi- parently ektexinous, with a lamellated inner foot- al examined (Fig. 1 H). Intine 2-layered, becoming layer (Fig. 2 E). Apertural exine largely absent (Fig. thickened in apertural region, with electron-dense, 2A, C, D). irregular vesicles in inner layer (Fig. 1 I). Exine of non-apertural region tectate-columellate, ektexin- Philydrelln (monotypic) ous, with prominent, apparently ektexinous lamel- P. pygmnen. - Grains 39 I'm, monosulcate, heter- he inner to the homogeneous foot-layer (Fig. 1 J). opolar (Fig. 3 A, D). Non-apertural wall finely rugu- Apertural exine composed of a verrucose sexine lose, apertural wall psilate to scabrate (Fig. 3B). and a thin, continuous nexine, the composition of Non-apertural intine 2-layered, with vesicular either obscure in material examined (Fig. 1 I). structures in the inner layer (Fig. 3E). Apertural

Grana 24 28 M. G. Sirripson

Fig.,4. Philydntnt lanicginositm. (A) Tetragonal tetrad of which is tectate-columellate in non-apertural wll (right), grains, equatorial view. Note distal apertures. SEM forming apparent thin, outer layer at aperture wall (left). X 1200. (B) Tetrad, polar view. SEM XWO. (C) Close-up Note thick, 2-layered intine (13 of aperture. TEM X2900. of one grain. Note coarsely reticulate nonapertural wall (G)Non-apertural Hall. Note lamellate inner foot-layer and psilate, hemispheric aperture (a). SEM X3 100. (D) (arrow) of exine (e). TEM X I1 OOO. (H) Apertural wall, Tetrad, in slightly oblique sagittal section. Note apertures showing thin, discontinuous exine layer (e) and thick, 2- (a), visible in two grains. TEM ~900.(E) Exine of two layered intine (3, with vesicles (arrow) in the inner intine contacting pollen grains. Note fusion in tectal region. layer. TEM ~7400. TEM ~14000.(F) Aperture interface. Note exine (e), Downloaded by [SDSU San Diego State University] at 10:35 25 February 2015

intine thick, 2-layered, with an electron-dense re- Pliilydnim (monotypic) gion between layers and with vesicles present in the P. laniiginosirm. - Grains 34 pm, monosulcate, inner 'layer (Fig. 3C, F). Exine of non-apertural heteropolar (apertures distal; Fig. 4D), shed in te- region tectate-columellate, apparently ektexinous, tragonal tetrad units (Fig. 4A, B). Wall of non- with a prominently lamellate inner foot-layer (Fig. apertural region coarsely reticulate (Fig. 4A, C), 3E). Apertural exine composed of a thin, continu- apertural wall psilate, somewhat hemispheric in ous layer of uncertain composition, with occasion- shape (Fig. 4A, B, C). Non-apertural intine thin, 2- al, tangentially flattened, apparently ektexinous layered (Fig. 4 G). Apertural intine thick, 2-layered outer elements (Fig. 3 F). (Fig. 4F), the inner intine layer with fine vesicular

Grana 24 Exine iiltrastriictiire of Plrilydraceae 29

C D ./

Fig. 5. Pfdydrrtrn lunrtginosrtm. (A) Basic fuchsin stain- (dark blue, at arrow) of inner apertural intine and moder- ing. Note positive (dark red) reaction of exine. x I OOO. (B) ate (light blue) staining of outer apertural intine. x 1700. Auramine 0 staining, showing positive fluorescence of (D) PAS treated, showing staining (light pink) of outer exine. ~800.(C) Alcian blue staining. Note dense staining intine layer (arrow). x 1700.

structures (Fig. 4H). Exine of non-apertural wall dark red; Fig. 5A) and positive aurarnine 0 fluores- tectate-columellate, apparently ektexinous, with a cence (fluorescing bright yellow; Fig. 5B). Inner Downloaded by [SDSU San Diego State University] at 10:35 25 February 2015 lamellate inner foot-layer (Fig. 4G). Exine tectal apertural intine alcian blue positive (staining dark region of adjacent grains fused at point of contact blue; Fig. 5C). Outer apertural intine layer PAS (Fig. 4 E). Apertural exine generally confined only positive (staining pink; Fig. 5D). to peripheral region of aperture (Fig. 4F), com- posed of a thin, apparently ektexinous layer and 1-2 subtending, electron-dense layers (Fig. 4 H). DISCUSSION All five species of the Philydnceae are palynologi- WALL CHEMISTRY cally similar in having monosulcate, heteropolar Philydritm laniiginosiim. - Exine of non-apertural pollen grains. The present study, thus, agrees with wall with positive basic fuchsin reaction (staining the observations of Hamann (1966), who described

Grana 24 30 Af. G. Sittipsoti

Ilelttiholtzia acorifolia as monosulcate and not 3- 1- to 3-layered exine wall architecture which lacks a sulculate as reported by Erdtman (1966). More im- typical tectate-columellate architecture (Simpson portantly, all members of the Philydraceae show 1983a). Although members of the Cyanastraceae, basic similarities in pollen wall architecture. For all Hypoxidaceae, Taccaceae, Pontederiaceae, and five species the exine of the non-apertural region is Velloziaceae have a tectate-columellate exine wall tectate-columellate with distinctive lamellae at- architecture (similar to’that of the Philydraceae), tached at the inner surface of the homogeneous this wall architectural type is common among an- foot-layer. In Pliilydrrrtii latirigitiosritti this exine giosperms as a whole (Walker & Doyle 1975) and wall stains positively with basic fuchsin and flu- probably primitive for this complex of monocotyle- oresces positively with auramine 0, both tests indi- dons (Simpson 19830, 6, 1985). cative of an ektexinous wall composition (Kress & In addition, the apertural intine of investigated Stone 1982). Preliminary histochemical studies by members of the Cyanastraceae, Haemodoraceae, the author indicate that the exine of the other four Hypoxidaceae, Taccaceae, and Pontederiaceae species is similarly ektexinous. The composition of consists of an inner fibrillar layer and an ortter layer the inner exinous lamellae could not be resolved infused with channels or vesicles, thus being oppo- from these histochemical tests. Based on TEM mi- site to that of the Philydraceae. Although the intine crographs, however, the lamellae appear similar in of all members of the Philydraceae shows structural structural composition and identical in staining resemblance (in location of vesicles) to that of some properties to the foot-layer, columellae, and tectum monocotyledonous taxa (e.g., grasses, such as Zea of known ektexinous composition. Because endex- ttiays; see Skvarla & Larson 1966, Kress & Stone ine generally has different TEM staining properties 1982), the pattern of staining is opposite to the from ektexine (Kress & Stone 1982), it is likely that common trend encountered among rnonocotyle- the lamellate structures of these taxa is ektexinous dons, including Zen (i.e., an outer pectic-rich “ex- in chemical make up. intine’,’ and an inner, predominantly cellulosic All family members show similarities in the com- “endintine”; Kress & Stone 1982). The signifi- position of the aperture wall. The apertural intine in cance of this “inversion” of inner’wallchemistry in all species is thick and 2-layered. Numerous vesicu- the Philydraceae is not at present known. lar structures are present in the inner intine layer; Of presumed Philydraceae relatives investigated an electron-dense fibrillar region usually occurs at to date, only certain species of Vellozin (Ayensu & the interface between inner and outer intine layers. Skvarla 1974) show some similarity to the Philydra- In Philydrim lanrtginosrini this inner, vesicular in- ceae in having a lamellate inner exine foot-layer and tine layer is pectic-rich (alcian blue positive) and in having grains shed as tetragonal tetrads, as in the outer intine layer is predominantly cellulosic Philydrritn. However, species of Vellozin differ (PAS positive). The exine of the apertural region is from Philydrrmi and other Philydraceae in having variable among members of the Philydraceae and an irregular to verrucate sculpturing, in lacking well may be absent (as in Orthothylax glaberrinirts) or defined apertures, and in having a very irregular consist of scattered, verrucose elements overlying tectate-columellate architecture in several species a thin, continuous nexine (all other species). From (Ayensu & Skvarla 1974). Thus, in view of the the present studies it is unclear as to the composi- differences in pollen grain sculpturing and aperture tion of these layers; both layers appear to have type between Pliilydrirm and Vellozin and consider- TEM staining properties similar to the ektexine of ing the numerous morphological differences be- Downloaded by [SDSU San Diego State University] at 10:35 25 February 2015 the non-apertural region. However, developmental tween the two families, it is questionable that the studies may be needed to determine whether one or tetragonal tetrad condition and inner lamellation in more of these layers might be endexinous instead. the two genera represent a shared evolutionary Few significant palynological similarities are event. noted between the Philydraceae and investigated Within the Philydraceae some minor palynologi- members of presumed relatives, thus providing no cal differences can be recognized between genera firm evidence for the interfamilial relationships as and species. The monotypic Philydrrim is unique in suggested, e.g., by Hutchinson 1973, Thorne 1981, the family in having grains shed in tetragonal tetrad and Dahlgren 1980. Members of the Haemodora- units, rather than as monads. Four species in three ceae are distinct from the Philydraceae in having a genera (Helmkoltzia acorifolia, H. tiovo-grrineen-

Grana 24 Exine iiltrastriictiire of Philydracene 3 1

sis, Orrliorliylax glaberriniris, and Philydrirni lanrr- Cronquist, A. 1981. An integrated system of classification gitiosiinz) have a reticulate nonapertural wall sculp- of flowering . - Columbia Univ. Press, New turing, that of Pliilydriini being very coarsely so. York. Dahlgren, R. 1980. A revised system of classification of Pliilydrelia, however, is distinguished from other the angiosperms. - Bot. J. Linn. SOC.80:91-124. family members in having a rugulate nonapertural Dahlgren, R. Rr Clifford, 11. T. 1982. The hfonocotyle- sculpturing. With regard to pollen size, Ilelnzlzolt- dons, a comparative study. - In: Botanical systemat- zin (25-26 p)and Orthothylax (22 Itm) are similar, ics: An occasional series of monographs. Vol. 2. - as are Philydrirni (34 pm) and Pliilydrclla (39 pm). Academic Press, New York. Engler, A. & Prantl, K. 1930. Die natiirlichen F'flanzen- The similarity in size between these pairs of genera familien. 2. Aufl. 15a: 190-191. - W. Engelmann, corresponds to the generic phylogeny of the Phily- Leipzig. draceae proposed by Hamann (1966). Erdtman, G. 1%6. Pollen morphology and taxon- In conclusion, the present study affirms the dis- omy. Angiosperms. Corrected reprint and new adden- dum. Hafner Publ. Co., New York. tinctiveness and homogeneity of the Philydraceae - Hamann, U. 1%6. Embryologische. morphologisch-ana- with respect to pollen ultrastructural characteris- tomische und systematische Untersuchungen an Phily- tics. Thus, although Erdtman (1966) described the draceen. - Willdenowia Beihefl4: 1-178. family as heterogeneous with regard to pollen unit Hams, P. J. & Hartley, R. D. 1980. Phenolic constituents and sculpturing, the wall ultrastructure of all family of the cell walls of . -Biochem. Syst. Ecol. 8: 153-160. members is identical in having: 1) ektexine IIennig, W. 1%6. Phylogenetic systematics. -The Uni- with distinctive lamellae at the inner surface of the versity of lllionois Press, Urbana. foot-layer; and 2) a 2-layered apertural intine with Hutchinson, J. 1934. The families of flowering plants, 1st vesicular structures concentrated in the itirier (ap- ed. vol 2, Monocotyledons. - Oxford Univ. Press, London. parently pectic-rich) layer. These features, together Hutchinson, J. 1959. The families of flowering plants, 2nd with the characteristic and apparently derived floral ed., 2, vol. 2, Monocotyledons. - Oxford Univ. structure in the Philydraceae (Hamann 1966) argue Press, London. strongly for the monophylesis of the family. The Hutchinson, J. 1973. The families of flowering plants, 3rd ed. - Oxford Univ. Press, London. -palynological characters in common between the Jensen, W. A. 1962. Botanical histochemistry - princi- Philydraceae and most presumed related families ples and practice. - W. H. Freeman & Co., San (including monosulcate, heteropolar grains and a Francisco. tectate-columellate exine architecture) are hypo- Kress, W. J. & Stone, D. E. 1982. Nature of the sporo- thesized to represent ancestral features, of no value derm in monocotyledons, with special reference to the pollen grains of Canna and Heliconia. - Grana in assessing phylogenetic history. Thus, a clarilica- 21: 129-148. tion of interfamilial relationships must await addi- Simpson, M. G. 1983a. Pollen ultrastructure of the IIae- tional data or future studies (especially rigorous modoraceae and its taxonomic significance. - Grana cladistic analyses) of existing data. 22: 79-103. Simpson, hi. G. 1983b. Systematics of the IIaemodora- ceae: Evidence from pollen ultrastructure, embryo- ACKNOWLEDGEMENTS logy, and anatomy. - PhD diss., Duke Univ., Dur- ham, North Carolina. This study mssupported in part by United States Nation- Skvarla, J. J. & Larson, D. A. 1%6. Fine structural al Science Foundation dissertation improvement awrd studies of Zea mays pollen. I. Cell membranes and grant, DEB-81-09909, and is largely derived from a Ph.D. exine ontogeny. - Am. J. Bot. 53: 11 12-1 125. dissertation submitted to the Department of Botany, Duke Spurr, A. 1969. A low-viscosity epoxy resin embedding University. I wish to thank Adrian Juncosa for aiding me medium for electron microscopy. - J. Ultrastruct. Downloaded by [SDSU San Diego State University] at 10:35 25 February 2015 in field collection in Queensland, Australia; Ulrich Ha- Res. 26: 31-43. mann for supplying me with fixed material of some family Takhtajan, A. 1980. Outline of the classification of flower- members; and the Arnold Arboretum for supplying dried ing plants (Magnoliophyta). - Bot. Rev. 46: 225-283. materials of Helniholizia now-guineensis. Thorne, R. F. 1976. A phylogenetic classification of the Angiospermae. - Evol. Biol. 9: 35-106. Thorne, R. F. 1981. New aspects and data in angiosperm classification, I. Intern. Bot. Congr., Sydney. REFERENCES - XI11 Australia. Abstracts: 121. Ayensu, E. S. & Skvarla, J. J. 1974. Fine structure of Walker, J. W. & Doyle, J. A. 1975. The bases of angio- Velloziaceae pollen. - Bull. Torrey Bot. Club sperm phylogeny: palynology. -Ann. Mo. Bot. Gard. 101:25&266. 62: 664-723. Grana 24