Int. J. Plant Sci. 153(4):589-601. 1992. ? 1992 by The University of Chicago.All rightsreserved. 1058-5893/92/5304-0008$02.00 DELAUBENFELS CUTICLE OFFALCATIFOLIUM MICROMORPHOLOGY (PODOCARPACEAE) RUTH A. STOCKEY,',*HELENKO,* AND PHILIPPEWOLTZt *Departmentof Botany, University of Alberta,Edmonton,AlbertaT6G 2E9, Canada;and tLaboratoirede MorphogeneseVegetale,Universite d'Aix, MarseilleIII, CentreSt. Jerome,France Cuticle micromorphologyof leaves from all five species of the SouthernHemisphereconifer genus Falcatifoliumde Laubenfels(Podocarpaceae)was studied with scanningelectronmicroscopy.Both herbariumand preservedspecimenswereexaminedand showedno differencesin micromorphology.External and internalfeaturesof abaxialand adaxialcuticles are characterizedfor the five species and compared to otherknownpodocarps.Externalcuticlesurfacesexhibitundulatingsurfacesthat may reflectunderlying epidermalcell outlines, stomatal plugs composed of irregularblocks, and fairly regularstomatal rows. Stomataare separatedby one to threeepidermalcells. Two lateralsubsidiarycells are presentwith polar subsidiarycells usually lacking. There is a deep crease in subsidiarycell cuticle, smooth to slightly undulatingcuticleon guardcell surfacesnearthe stoma, a ridgeon guardcell cuticle,thin cuticularflanges between guard and subsidiarycells, polar extensions, nonsinuous epidermalcell outlines with cuticle extendingto the hypodermis,more elongate epidermalcells between stomatal rows than within rows, and usuallygranularepidermalcell surfaces. Introduction The genus Falcatifoliumde Laubenfels(Podocarpaceae)contains five species that range from Malaysia to the Philippines and New Caledonia (de Laubenfels 1969, 1972; Silba 1986). These are reportedlydioecious shrubs or trees that are distinguishedfrom the other podocarpsby their sickle-like or falcate, laterally flattened, spirally arrangedleaves with twisted bases that spread out distichously from the branch (de Laubenfels 1969; Silba 1986). The name Falcatifoliumrefers to the basal falcatecurvatureof leaves away from the branch(de Laubenfels 1969). The genus Falcatifoliumwas split from DacrydiumSolanderex Lambert, Florin's (1931) "Gruppe A," by de Laubenfels(1969), based on its fertile structures, which are producedon specializedaxillaryshoots; a pronounced "hump" on the epimatium that projects laterally from the mature cone; pollen morphology;and lack of vascularfibersin leaves (Tengner 1965), as well as on general leaf morphology. Cuticularstudies of the Podocarpaceae,while numerous, have neglected some of the less accessible species. The family is a large one with over 170 species (Silba 1986). Leaf structureand cuticle morphologyat the light microscope (LM) level of some specieswerestudiedby Florin(1931, 1940a, 1940b, 1958), Orr (1944), Buchholz and Gray (1948a, 1948b, 1948c), Gray and Buchholz (1948, 1951), Townrow (1965, 1967a, 1967b, 1969), Dilcher (1969), Schoonraadand Van Der Schijff(I974), Ferreet al. (1977), and Greenwood (1987). Scanning electron microscopy (SEM) of epicuticularwaxes (Morvan 1982, 1987) and leaf morphology of some taxa have been examined recently (Stockey and Ko 1988, 1990; Cantrill ' Author for correspondenceand reprints. rereceivedJanuary1991; revisedmanuscript Manuscript ceivedJuly1992. 589 1989; Wells and Hill 1989a, 1989b). Leaves of Falcatifolium taxoides (= Dacrydium taxoides) from New Caledonia have been examined using LM by Greenwood(1987) and by SEMby Stockey and Ko (1988), while the four other taxa in this genus have not so far been examined micromorphologically.Greenwood(1987) also studied F. falciforme (Parlatore) de Laubenfels and F. papuanum de Laubenfels with LM but did not include detailed descriptions or any illustrations of the cuticleof thesetaxa. He distinguishedleaves of Falcatifolium from those of other podocarps; however,severalcuticularcharactersoverlapwith those of Dacrycarpus(Endl.)de Laub.and Nageia Gaertner (= Decussocarpusde Laub.). The usefulness of SEM and its importance in taxonomy have been emphasized in recent years (Wells and Hill 1989a).Becauseof the complexreliefof many gymnosperm cuticles, SEM has been shown to provide more detail than is possible with the light microscope(e.g., Stockeyand Ko 1986;Wellsand Hill 1989a). In this paperwe examine micromorphological featuresof all five currentlyrecognizedspecies of Falcatifoliumusing SEM. The micromorphological similarities are assessed to determine which characterscan be used most consistently for taxonomic purposes. The usefulness of micromorphological cuticular features in distinguishing these taxa is examinedand comparisonsaremade between these and other known podocarps. Materialandmethods Leaves of all species were examined from herbarium material(table 1). In addition, preserved specimens of Falcatifolium taxoides were also used. No cuticular differenceswere observed in leaves preservedin FPA (5 mL formaldehyde,5 mL propionicacid, 90 mL 50%ethanol)and dried herbariumspecimens. All leaves were sectioned with the leaf margins OF PLANT SCIENCES JOURNAL INTERNATIONAL 590 Table1 FALCATIFOLIUM DE LAUBENFELS Material examined F. angustum de Laubenfels ............. Source Voucher Herbarium Typea Species H H K K E. F. Brunig 5963 J. A. R. Anderson 2448 Sarawak Sarawak H MO 2728237 P. J. Martin S.37583 F. gruezoi de Laubenfels ................ H CAHUP Gruezo and Hemaz 27033 F. papuanum de Laubenfels ............. H MO 3058387 K. Kerenga 3 F. taxoides (Brongniart et Grisebach) de Laubenfels ............. H, P UAPC-ALTA McPherson and Stockey 3960D Gunong Santubong 1st division, Sarawak Oriental Mindoro, Phillippines Menyamya, Morobe, New Guinea Road to Mt. Dzumac, Dumbea Valley New Caledonia F. falciforme(Parlatore) de Laubenfels ........................ a H = herbarium specimen, P = preserved specimen. intact,leavingboth abaxialand adaxialepidermis attached for cuticle examination. All preparations were rehydratedin distilled water for 24 h and then immersed in 20% CrO3 (chromium tri- oxide) solution for 96 h (Alvin and Boulter 1974; Stockey and Ko 1986). Approximately 10 leaves of each species were examined with SEM. Stomatal distributionwas determinedby examining leaves on several brancheswhen specimens were available. Cuticles were washed in distilled water, air dried, and mounted on stubs with silver conductive paint. Both inner and outer surfaces were examined by SEM. Specimenswere sputtercoated with 150 A Au on a Nanotek Sputter Coater and examined with a CambridgeStereoscan250 at 20 kV. All stubs are deposited in the University of Alberta Paleobotanical Collection (UAPCALTA). Stomataldistributionwas determinedby the examination of leaves from several branches. Descriptions disregardwhat is obvious debris on cuticle surfaces.Photographswere taken with the long axis of the leaf parallel to the long axis of the plate,and stomatalorientationsaregiven with respect to that axis. Results ANGUSTUM FALCATIFOLIUM (FIGS.1-8) Adult leaves of this speciesfrom Sarawak(table 1), are 18-35 mm long by 1-2.5 mm wide (table 2). The externalcuticle surfaceis undulatingwith outlines of underlyingepidermalcells clearlyvis- Table2 FEATURES ON LEAVES OF FALCATIFOLIUM EXTERNAL CUTICULAR Species Leaf dimensions (length x width in mm)a F. angustum ... 18-35 x 1-2.5 Present Irregular blocks, perforate F. falciforme .. 20-65 x 5-7 Present/absent on same leaf F. gruezoi ..... 3.5-20 x 3.5-7 Present/absent on same leaf F. papuanum 12-17 x 2-3.5 Present/absent on same leaf 10-31 x 3-6 Absent/present sunken Solid, irregular blocks or sheets Irregular blocks, or entire stoma blocked Irregular blocks, granular to solid Solid, irregular blocks F. taxoides a .... Florin ring From Silba (1986), and personal observation. Stomatal plug Stomatal distribution Discontinuous rows, both surfaces except on midrib Discontinuous but extensive rows, both surfaces, except on midrib Discontinuous rows, both surfaces, except on midrib Discontinuous rows, both surfaces, except on midrib Discontinuous but extensive rows, both surfaces, except on midrib Stomatal orientation to long axis of leaf Parallel Parallel Parallel Parallel Parallel I' 'v ~~~~~~~SO- V~ Figs.1-8 Falcatifolium angustum. Fig. 1, Inner surface,reeion of stomatal apparatuswith two subsidiarycells; x 1,500. Fig. 2, Innersurface,stomatalrows, showingtwo and threesubsidiarycells per stomatalapparatus;x 310. Fig. 3, Innersurface, stomatalrow; x 280. Fig. 4, Innersurface,epidermalcell outlines; x 280. Fig. 5, Outersurface,showingundulatingepidermal cell outlines and Florin rings. Several stomata show plugs; x 488. Fig. 6, Inner view, cuticle on guard and subsidiarycell surfaces;x 3,100. Fig. 7, Inner surface,epidermalcell surfacecuticle; x 3,100. Fig. 8, Outersurface,Florin ring surrounding stoma with plug; x 1,600. 592 INTERNATIONAL OF PLANT SCIENCES JOURNAL Table3 INTERNAL CUTICULAR FEATURES (AM) ON LEAVES OF FALCATIFOLIUM Epidermal cell dimensions Species F. angustum ... F. falciforme ... F. gruezoi F. papuanum . . F. taxoides .... Stomatal dimensiong (polar x lateral) 42 39 52 37 41 x x x x x 38 36 41 39 45 No. subsidiary cells 2 2 2 2 2 common, common, common, common, common, 3 3 3 3 3 occur occur occur occur rare, 4 rare ible (fig. 5). Stomatal plugs are irregular,composed of block-like components (table 2) and are often perforatedby channelsor free nearthe edge (figs. 5, 8). Prominent upraised Florin rings (Buchholz and Gray 1948a) surround the stomata. Rings may be complete or interrupted(fig. 5) and reflect the underlyingpattern of the stomatal apparatus. Stomatain discontinuousbut fairlyregularrows are oriented parallel to the leaf axis (figs. 2, 3; table 2). Polar subsidiarycells are often missing (table 3; fig. 1). Stomata are situated close to one anotherusually with one elongate,epidermalcell between them (fig. 2). The presenceof this cell is also noticeable on external cuticle surfaces (fig. 5). Two subsidiarycells are most common with three occasionally arising from the division of a lateral subsidiarycell (fig. 2, top). Cuticle on the subsidiarycells is often rugoseand longitudinally striated (figs. 1, 6). A deep crease or groove is often seen in this cuticle surface corresponding on the external surfaceto the Florin ring (fig. 1). The flangeof cuticle between guardcells is relatively thin and slightlyrugose(fig. 6). Cuticleon guardcell surfacesis smoother toward the stoma to more rugosetowardthe lateral,subsidiarycells (fig. 6). A distinct rugose ridge occurs near the lateral edge of the guard cell cuticle. The flange between guardand subsidiarycells is slightly rugose, often with an inrolled edge that partially surroundsthe guard cells (figs. 1, 6). Small ribbon-like polar extensions are found but are often broken or curled in preparationsrevealing their delicate nature (fig. 2). Epidermalcells surroundingthe subsidiarycells are shorterand often broaderthan those between (length x width) Between Within stomatal stomatal bands bands 91 67 40 38 87 x x x x x 16 21 13 13 14 37 12 9 16 46 x x x x x 17 6 8 10 17 Epidermal cell surface Rugose, enlarged pits Rugose and pitted Pitted usually, to smooth Smooth to slightly pitted Rugose and pitted stomatal rows (figs. 2, 3). There are usually one or two lateralepidermalcells opposite each lateral subsidiary cell (fig. 2). Cuticular flanges on epidermalcells are not sinuous (fig. 4), and irregular flangesoften extend to the hypodermallevel (fig. 2, upper left). Cuticle on epidermal surfaces is rugose and pitted (fig. 1; table 3) with extensive channels into the cuticle sometimes visible (fig. 7). FALCATIFOLIUM FALCIFORME (FIGS. 9-22) Adult leaves of this species were collected from a coastal area in Sarawak(table 1) from a tree 4 m tall. The externalcuticle surfaceis undulating with epidermal cell outlines clearly visible (fig. 11). Cuticle on epidermal cell surfaces between stomatal bands often shows a large number of small undulations on the surface (figs. 11, 16), while surroundingepidermalcells have relatively smooth cuticular surfaces(figs. 11, 12, 15). Stomatal plugsare fairlysolid and appearto be composed of irregularblocks or sheets (figs. 15, 17; table 2). ProminentupraisedFlorin ringsare usually seen surroundingthe stoma (figs. 11, 12, 1517). Rings may be complete or interrupted(fig. 12) and reflect the underlyingpatternof the stomatal apparatus. Occasional double rings have been observed (fig. 16). On some areas of a leaf, Florin rings may be lacking (fig. 13), while they are present on other areas of the same leaf. Stomata are in discontinuous but fairlyregular rowsthat are orientedparallelto the leaf axis (figs. 10, 14; table 2). Polar subsidiarycells are lacking (figs. 10, 14, 19, 20), and cell flanges of lateral subsidiarycells can be found in contact with one another (fig. 9). Stomata are situated close to one Figs.9-22 Falcatifoliumfalciforme.Fig. 9, Innersurface,region of stomatalapparatuswith two subsidiarycells and ribbonlike polarextensions(PE); x 1,800. Fig. 10, Innersurface,stomatalrows; x 150. Fig. 11, Outersurface,showingFlorinrings, epidermalcell outlines and rugosetextureof epidermalcells not in stomatalband; x 165. Fig. 12, Outer surface,Florin ring with modified polar regions reflectingthe underlyingcell structure;x 400. Fig. 13, Outer surfaceof same leaf as in fig. 12, showing lack of Florin rings or slightlydepressedrings; x 135. Fig. 14, Inner surface;stomatalbands showingtwo and three subsidiarycells per stomatalapparatus;x 270. Fig. 15, Outersurface,Florin rings,stomatalplugs, and smooth cuticle texture on epidermalcell betweenstomata; x 650. Fig. 16, Outersurface,showingdouble Florinringand rugoseepidermalcell cuticle outside the stomatalband; x 230. Fig. 17, Outersurface,Florinringand sheetlikestomatalplug; x 1,350. Fig. 18, Innerview, U'~~~~~~~~~~~~~~~~~~~~~~~~~~F Si 1 1O1(e1 onguard cuticle cellsurface; x 3,600.Fig.19,Inner surface, rowwithsubsidiary stomatal cellwallflanges incontact; x 650. Fig. 20, Inner surface,region of stomatal apparatus;x 1,700. Fig. 21, Innerview, cuticle on epidermalcell surface;x 1,650. Fig. 22, Inner surface, two stomata sharingtwo subsidiaryr cells. Note encirclingcell at right with cuticle micromorphology similar to its adjacentsubsidiarycell; x 875. 594 INTERNATIONAL JOURNAL another with one to three interveningepidermal cells (figs. 10, 14). Occasionally closely spaced chains of stomata are seen without intervening epidermalcells (fig. 19). Two subsidiarycells are most common with three occasionally arising from the division of a lateral subsidiarycell (fig. 14). One double stomatalapparatuswas observed with four guardcells sharingtwo subsidiarycells (fig. 22). Furthermore,one of these lateral subsidiary cells probably divided longitudinally to produce a third cell with cuticular micromorphologyidenticalto that on lateralsubsidiarycells (fig.22). Cuticleon subsidiarycells is rugose,usually with a thick outer wall flange with lateral undulations (fig. 9). Striations are not common as in F. angustum, but a deep crease or groove is often seen in this cuticle surface(figs. 9, 18, 20, 22) correspondingto the external Florin ring. The flangeof cuticle betweenguardcells is thin and relatively smooth (figs. 18, 20). Cuticle on guard cell surfaces is smooth toward the stoma and slightly more rugose near the subsidiarycell wall flange(fig. 18). A distinct ridgeis presenton the guard cell cuticle with a prominent, inrolled edge on the flangebetween guardand subsidiary cells (figs. 9, 18, 20). Polar extensions are pronounced, fairly thick, and often exhibit a central ridge (figs. 9, 18-20). Epidermalcells surroundingthe subsidiarycells are shorter,broader,and more irregularin shape than those between stomatal rows (fig. 10; table 3). If stomatal rows are closely spaced, the intervening epidermal cells are broader and shorter than those between widely spaced rows (fig. 10). Cuticularflanges on epidermal cells are not sinuous (figs. 10, 14), and irregularflangesmay extend to the hypodermallevel (fig. 14). Cuticle on epidermal cell surfaces is rugose and pitted (fig. 21) but lacks the extensive channeling as in F. angustum (fig. 7). FALCATIFOLIUM GRUEZOI (FIGS. 23-33) Adult leaves of this species were obtainedfrom an isotype specimen from Oriental Mindoro in the Philippines(table 1). Externalcuticle surfaces are undulatingwith epidermal cell outlines partially visible (fig. 28). Cuticle on epidermal cell surfacesbetween stomatal bands on some leaves shows a number of small undulations (fig. 28) like those in F. falciforme. These, however, are not as pronouncedas in F. falciforme and do not occur on all leaves examined (fig. 30). Stomatal plugs are composed of irregularblocks (fig. 26); or stomata are also completely blocked with cuticle (figs. 28, 30). Prominent Florin rings are often seen around stomata and may be complete or interrupted(figs. 28, 30). They may, however, be lackingespeciallyaroundpluggedstomata(figs. 28, 30). Stomata are in closely spaced discontinuous OF PLANT SCIENCES rows that are oriented parallelto the long axis of the leaf (figs. 25, 27; table 2). Polar subsidiary cells are lacking(figs. 23, 27, 29, 32), and the two lateralsubsidiarycells may be in contact as in F. falciforme. Stomatain a row are usuallyseparated by one to three interveningepidermal cells (figs. 25, 27, 29, 32). Two subsidiary cells are most common, with three occasionally arising from a division of a lateral subsidiarycell (figs. 29, 33). One double stomatalapparatuswas observedwith four guardcells sharingthree subsidiarycells (fig. 33). Cuticle on subsidiarycell surfacesusually appears as two broad winglike flanges that often show a thin irregularouter flange (figs. 23, 32). This cuticularflange can also be thicker when it coincides with an epidermalcell wall flange(figs. 27, 29, 33). Occasionally, lateral undulations of this outer flange are seen as in F. falciforme (fig. 29). In general,cuticle on subsidiarycell surfaces is smooth to slightly rugose (figs. 23, 33). Striations have not been observed as in F. angustum, but a deep crease or groove is present in this cuticle surface(figs. 23, 27, 29, 32, 33) as in other Falcatifolium species. The flangeof cuticle betweenguardcells is thin and relatively smooth (figs. 23, 31) as in F. falciforme. Cuticle on guardcell surfacesis smooth toward the stoma and slightly more rugose near the subsidiary cell wall flange (fig. 30). A ridge also occurs on the guardcell cuticle surfaceas in other Falcatifolium species (figs. 23, 33) but is not as prominent. The flangebetween guardand subsidiarycells also has an inrolled edge (figs.23, 31), which again is not as prominent as in other species. Polar extensions are pronounced with a central ridge (figs. 23, 27, 29, 33) as in F. falciforme. Epidermalcells are more irregularin shapethan in the previously described species but generally more elongatebetween stomatalrows and shorter when near the stomatal apparatus(figs. 25, 27; table 3). Cuticularflanges on epidermal cells are not sinuous, and irregularflangesmay extend to the hypodermal level (figs. 25, 27). Cuticle on epidermal cell surfacesis pitted (fig. 24) but less rugose than F. angustum or F. falciforme. PAPUANUM(FIGS. 34-45) FALCATIFOLIUM Adult leaves of this species were obtainedfrom a tree 8 m high from Menyamya, Morobe, New Guinea (table 1). Externalcuticle surfacesare undulating;however, underlyingepidermalcell outlines are not as visible as in other Falcatifolium species (fig. 39). Stomatalplugs are irregularwith block-like,granularcomponents(figs. 34, 38, 42). Florin rings are present in some areas of the leaf (figs.37, 43), while only slightlyraisedareasoccur in others (fig. 39). On some leaves the whole area .4i ~~~~~~~~~ Figs.23-33 Falcatifoliumgruezoi.Fig. 23, Innersurface,view of stomatalapparatuswith two subsidiarycells, x 1,350. Fig. 24, Innerview, cuticle on epidermalcell surfaces;x 650. Fig. 25, Innersurface,stomatalrows; x 235. Fig. 26, Outersurface, Florin ring and stomatal plug; x 1,025. Fig. 27, Inner surface,stomata with two and three subsidiarycells; x 470. Fig. 28, Outer surfaceshowing epidermalcell outlines, Florin rings, and partialrings aroundpluggedstomata; x 225. Fig. 29, Inner surface, stomata with two and three subsidiarycells; x 725. Fig. 30, Outer surface,Florin rings, partialrings, and plugged stomata; x 230. Fig. 31, Innersurface,cuticle on guardcell surfaces;x 4,000. Fig. 32, Innersurface,stomatalrow with broad subsidiarycell wall flanges; x 700. Fig. 33, Inner surface,stomatalgroupwith four guardcells sharingthree subsidiarycells; x 1,250. OL~t Figs.34-45 Fakcatifolium papuanum.Fig. 34, Innersurface,regionof stomatalapparatusshowingthree subsidiarycells (SC) and ribbon-likepolarextensions(PE); x 1,800. Fig. 35, Innersurface,stomatalrows; x 175. Fig. 36, Innersurface,epidermal cell outlines; x 230. Fig. 37, Outer surface,Florin ringand stomatalplug; x 1,400. Fig. 38, Innersurface,stomatalband with two and threesubsidiarycells per stomatalapparatus;x 938. Fig. 39, Outersurface,showingstomatalplugsand lack of distinct Florin rings; x 185. Fig. 40, Inner view, cuticle on guardcell surface;x 3,750. Fig. 41, Innerview, cuticle on epidermalcell surface;x 1,000. Fig. 42, Outersurface,stomatalplug morphology;x 5,250. Fig. 43, Outersurface,stomatalrow with Florin STOCKEY ET AL.-FALCATIFOLIUM of the stomatalrow is upraisedresultingin a chain of Florin rings (fig. 43). Stomatain discontinuousbut fairlyregularrows are oriented parallel to the long axis of the leaf (fig. 35;table 2). As in otherFalcatifoliumspecies polar subsidiary cells are lacking, and as in F. falciforme lateralsubsidiarycell wall flangesmay be in contact or connected to the polar extension (figs. 34, 38, 44). Stomata are usually separated from one another by one to three intervening epidermal cells. Two subsidiary cells are most common, with three rarelybeing the result of the division of a lateral subsidiarycell (figs. 34, 38, 45). One stomatal apparatuswas observed with four guard cells sharingtwo subsidiarycells (fig. 45). Cuticle on subsidiarycell surfacesusually appears as two broad flanges, the outer edges of which may be thin and, as in F. gruezoi, thicken when coincidingwith an epidermalcell wall flange (figs. 34, 38, 44, 45). Cuticle on subsidiarycells is rugose(figs. 34, 44), sometimes showinglateral undulations(fig.38) and horizontalstriations(fig. 44). A deep crease or groove is usually seen in this cuticle surface (figs. 38, 44) as in other Falcatifolium species. The flangeof cuticle betweenguardcells is usually thin and relatively smooth (figs. 40, 44). Cuticle on guard cell surfaces is smooth to undulating near the stoma and more rugose toward subsidiarywall flanges(figs.34,40,44). A distinct ridge can occur on this cuticle surface (fig. 44) and a prominent inrolled edge of the flange between guard and subsidiary cells (fig. 34). Polar extensionsarepronounced,fairlythick, and often exhibit a central ridge (figs. 34, 38, 44, 45). Epidermalcells surroundingthe stomatal apparatusare shorterand often broaderthan those between stomatalrows (fig.35; table 3). Cuticular flanges on epidermal cells are not sinuous (fig. 36). Cuticle on epidermalcell surfacesis smooth to slightly rugose (fig. 41); however, pitting or channelshave not been observed as in other Falcatifolium species. FALCATIFOLIUM TAXOIDES (FIGS.46-53) The external cuticle shows slight undulations (fig. 52). Stomatal plugs are composed of blocklike components, and upraisedFlorin rings have not been observed (fig. 52). The stomata show three levels of cuticular thickening around the stomatal apparatus.The stoma is surroundedby a ring that is in turn surroundedby a higherlevel ringthat may be interruptedat the poles (fig. 52). CUTICLE 597 The inner sunken ringlike zone corresponds to the position of the Florin ring in other Falcatifolium species and the deep crease in subsidiary cell cuticle internally.The outer ringcorresponds to the outeredge of the subsidiarycell wall cuticle internally (e.g., fig. 46). The leaves observed in this study show deep creasesin the subsidiarycell wall cuticle and, therefore,what might be interpretedas a partiallysunken Florin ringexternally (fig. 52). Stomatalrowsarediscontinuous,fairlyregular, with stomata oriented parallelto the long axis of the leaf (figs. 47, 49; table 2). Polar subsidiary cells are usuallylacking,with two subsidiarycells being the most common condition (figs. 47, 49). However, during the present study we found a few stomata with three or four subsidiary cells (fig. 51). Stomata are usually separatedby one to three intervening epidermal cells (figs. 47, 49). On some parts of a leaf an epidermal cell in the terminal position may have the appearanceof a polar subsidiary cell, but an intermediate morphology of the cuticle is present (fig. 53). In one leaf a pair of stomata are separated by an epidermal cell but have adjoining subsidiary cells (fig. 51). One of the stomatal apparati is larger than the other, and the two lateralsubsidiarycells have divided to produce four, resultingin an unusual morphology for the pair (fig. 51). Cuticleon subsidiarycell surfacesis rugoseand may show longitudinalstriations(figs.46, 53), as in F. angustum. The outer subsidiary cell wall flange is usually very irregular(figs. 46, 51, 53). A deep crease or groove occurs in this cuticle (Stockey and Ko 1988) as in other Falcatifolium species (figs.46, 53). When these grooves are shallow, a rugose ornamentationcan be seen on the subsidiarycell surface(figs.48, 51). Irregularpeaks of cuticle also occur in this region (fig. 51). The flangeof cuticle between guardcells is thin and relatively smooth to slightly rugose (fig. 48). Cuticle on guardcell surfacesis smooth near the stoma with slight undulations gradingto rugose approachingsubsidiarycells (figs.46,48). A ridge is present on the guard cell cuticle as in other Falcatifolium species (figs. 46, 48, 51, 53). The cuticularflangebetweenguardand subsidiarycells has an inrollededge (fig.48). Polarextensions are delicate, sometimes elongate (fig. 51), with a central ridge (figs. 46, 53). Epidermal cells are distinctly shorter and broaderwhen in contact with a stomatal row and more elongate between rows (figs. 47, 49; table 3). Cuticular flanges on epidermal cells are not ringsand raisedcuticle on polarepidermalcells; x 525. Fig. 44, Innersurface,regionof stomatalapparatusshowingtwo lateral subsidiarycells; x 150. Fig. 45, Inner surface,stomatal row with four guardcells sharingtwo subsidiarycells and abnormal subsidiarycell divisions on lower stomatalapparatus;x 725. 7 4 4~~~~~~~~~~~~~~~~~~~~~~4 Falcatifoliumtaxoides. Fig. 46, Inner surface,region of the stomatalapparatusshowingtwo subsidiarycells; 1,400. Fig. 47, Innersurface,stomatalrows; x 150. Fig. 48, Innerview, cuticle on guardand subsidiarycell surfaces;x 3,000. Innersurface,stomatawith two and threesubsidiarycells; x 270. Fig. 50, Innerview, cuticleon epidermalcell surfaces; Fig. 49,46-53 Figs. x ,0.Fig. 51, Inner surface,stomatal pair sharingseven subsidiarycells; x 750. Fig. 52, Outer surface,showing sunken Flrnrngs and stomatal plugs; x 550. Fig. 53, Inner surface,stomatal apparatuswith three subsidiarycells and one polar eiemlcell; x 1,750. STOCKEY ET AL.-FALCATIFOLIUM sinuous, and irregularflanges may extend to the hypodermal level (figs. 47, 49, 50). Cuticle on epidermal cell surfacesis rugose, pitted (fig. 50), and may be channeled as in F. angustum. Discussion With the present study of Falcatifoliumwe are now able to characterizethe cuticle micromorphology of all five species within the genus. The genus itself is characterized micromorphologicallyby undulatingoutercuticlesurfacesthat may reflectthe underlyingepidermalcell outlines;stomatal plugs composed of irregularblocks; fairly regularstomatal rows; stomata separatedby one to three epidermal cells; two lateral subsidiary cells present, with polar subsidiary cells usually lacking; a deep crease in subsidiary cell cuticle; smooth to slightly undulating cuticle on guard cell surfacesnear the stoma; a ridge on guardcell cuticle;thin cuticularflangesbetweenguardcells; rolled cuticular flanges between guard and subsidiary cells; polar extensions; nonsinuous epidermal cell outlines with cuticle extendingto the hypodermis; more elongate epidermal cells between stomatal rows than within rows; and usually granularepidermal cell surfaces. The presenceor absence of Florin ringscannot be used as a diagnostic feature within the genus Falcatifoliumsince on one leaf this charactervaries considerably. Upraised Florin rings do not occur in F. taxoides, but sunken rings do occur in some cases. In F. falciforme, F. gruezoi, and F. papuanum they are present on some areas of a leaf and absent on others, while in all leaves examinedofF. angustumtheywerepresent.While this feature is consistently present within other genera of conifers, e.g., Agathis (Page 1980; Stockey and Atkinson 1988), and is diagnostic for those genera,this is not so with Falcatifolium. One of the micromorphologicalcharactersthat appearsto be most useful for taxonomic purposes is subsidiarycell cuticle micromorphology.Vertical striationsappearin F. angustumand F. taxoides and horizontal striations in F. papuanum. Granularityvariesbetweenthe taxa, with F. gruezoi having the smoothest subsidiarycell wall surface flanges.Thickness and outline of this cuticle appearto be taxonomically significantin the five species. While all taxa show creases or grooves near the guardcells, only in the New Caledonian species, F. taxoides, are they shallow enough to reveal peaks of cuticle and a granularornamentation in the groove. Similar cuticle in this zone was reported in the Araucariaceaein Araucaria humboldtensisBuchholz (Stockeyand Ko 1986), also from New Caledonia. Cuticle on epidermalcell surfacesis smoothest in F. papuanum, then F. gruezoi, slightly more granularin F.falciforme,and distinctlypitted and CUTICLE 599 channeled in F. taxoides and F. angustum. Cuticle on guard cell surfaces,while generallysimilar, also varies in rugosity, with F. gruezoi, F. falciforme, and F. papuanum being generally smoother over all, while F. angustumand F. taxoides are more rugose. Externally,epidermal cell undulationsmay be slightlydiagnostic.Many fine undulations occur on the surfaces of epidermal cells between stomatal rows in F. falciforme and fewerin F. gruezoi.These undulationsare lacking in the other species. The genus Falcatifolium shows many similarities in cuticle micromorphologyto Dacrydium, from which it was originally segregated(de Laubenfels 1969). Stomata, as in most Podocarpaceae (Florin 1931; Greenwood 1987), are oriented parallel to the long axis of the leaf; polar subsidiarycells are absent.Thereare deep creases in subsidiary cell cuticle, and polar extensions occur (Stockeyand Ko 1990). However, Dacrydium species so far examined have sinuous epidermal cell outlines and striationsat the bases of epidermal cell buttresses (Wells and Hill 1989a; Stockey and Ko 1990). Smooth epidermal cell cuticle (Stockeyand Ko 1990) as well as granular surfaces (Wells and Hill 1989a) have been recorded and Florin rings,while lackingin the New Caledonian species examined (Stockey and Ko 1990), are reported to be present but variable within the genus (Wells and Hill 1989a). Among the broad-leavedpodocarpaceoustaxa that may be compared micromorphologicallyto Falcatifolium,the genusAcmopylePilgerhas polar subsidiarycells in greaternumbersand smooth epidermal cell surface cuticle and lacks Florin rings (Stockeyand Ko 1988). Nageia Gaertner(= Decussocarpusde Laubenfels) have four to six subsidiary cells, usually with two polar subsidiaries (Stockey and Ko 1988). The genus PrumnopitysPhil. shows some similaritiesto Falcatifolium, often lacking polar subsidiary cells, but subsidiary cell cuticle is quite distinctive with lateralstriationsand a very rugosetexture(Stockey and Ko 1988). Imbricate-leavedtaxa were recently described micromorphologicallyby Wells and Hill (1989a). Dacrycarpus(Endl.) de Laubenfels leaves have stomata parallelto the long axis of the leaf as in Falcatifolium;however, these stomata are interpreted as paratetracytic,i.e., with two elongate lateral subsidiarycells parallelto the guard cells and two narrowpolar cells (Dilcher 1974). While it is difficult to assess the epidermal cell surface morphology from the limited number of photographs presented by Wells and Hill (1989a), it appearsthat at least some of the polar subsidiary cells in Dacrycarpusdacrydioides(Rich.) de Laubenfels, e.g., have epidermalcell micromorphology as in Falcatifoliumreportedhere. Apparently, the presenceof Florin rings is also variable in 600 INTERNATIONAL JOURNAL this genus (Wells and Hill 1989a). Polar extensions occur in Dacrycarpusthat are very similar to those reported in Falcatifolium species here. From the descriptionpresentedby Wells and Hill (1989a), we cannot distinguish this cuticle from that of Falcatifolium.An amplificationof the information on this taxon is required for further comparison. The generaHalocarpusQuinn, Lepidothamnus Phil., and LagarostrobusQuinn have randomly oriented amphicyclic stomata (Wells and Hill 1989b) and are, thus, quite different than the regularlyoriented stomata of Falcatifolium described here. MicrocachrysHook. f. ex Hook., the Tasmanian endemic, does have regularstomatal rows but shows irregularlyshaped subsidiary cells, many of which are shared by adjacent stomata, and lacks polar extensions (Wells and Hill 1989a). Cuticle of MicrostrobosGarden et Johnson is similar to that of Microcachryswith shared subsidiary cells present, and one of the (F. Muell.)Gard. species,Microstrobosfitzgeraldii et Johns. also lacks polar extensions (Wells and Hill 1989a). Parasitaxusde Laub.,the New Caledonian parasitic conifer, has irregularlyshaped subsidiarycells, with variable orientation to the guard cells, and shows some similarity to Lepidothamnus(Wells and Hill 1989a). Leaves of all of these taxa, however, can also be easily separated from Falcatifolium on the basis of their external morphology. Fossil leaves of Falcatifolium have been reported from the Miocene of Antarctica (Zastawniak 1981) and the Eocene of Australia (Greenwood 1987). The Antarcticmaterialis impression materialonly; thus, cuticle has not been described. Fossil cuticles of Falcatifoliumwere described by Greenwood (1987). Falcatifolium australis Greenwood, unlike the extant species, has sinuous epidermal cell outlines, leaves that are generallysmallerthan living taxa, and stomatamostly on the abaxial surface. Greenwood (1987) compares F. australis to F. papuanum with respect to stomatal apparatusmorphology and to F. falciforme based on vegetative morphology. OF PLANT SCIENCES This study, however, utilized only light microscopy, and certain cuticular features remain obscure using that mode of investigation. The lack of polar subsidiary cells reported in the present study for Falcatifolium is based on the cuticular micromorphologyof cells in the polarregion.The epidermalcells in the position of polar subsidiary cells have a morphology like that on the surroundingepidermalcells. The same situation occurs in species of PodocarpusL. Herit. ex Pers. (personal observation) and sometimes in Prumnopitys (Stockey and Ko 1988) and Dacrydium (Stockey and Ko 1990). Thus, the small cells in the position of polar subsidiarycells are, in fact, epidermal cells based on micromorphology. We hope that studies of extant conifer cuticles at the micromorphologicallevel will serve as the basis for comparison in future paleobotanical work (e.g., Wells and Hill 1989b). Within the Podocarpaceaeand Araucariaceae,cuticle micromorphology has already proven to be useful in the systematic description of several fossil SouthernHemisphere taxa (Cantrill 1989; Wells and Hill 1989b; Hill and Carpenter1991). Since many extant podocarpaceoustaxa have not yet been described,it is criticalthat they be well documented for future reference. Acknowledgments We thank the following for help in obtaining specimens:Dr. Peter H. Raven, Missouri Botanical Garden; Dr. Peter Edwards, Royal Botanic Gardens,Kew; Dr. William Gruezo, Herbarium, Museum of Natural History, University of the Philippinesat Los Banos, Laguna.Specialthanks to Dr. Gordon McPherson, Missouri Botanical Garden, for extensive help in the field; George Braybrook,Departmentof Entomology,University of Alberta, for technical assistance;and Dr. Gar W. Rothwell, Department of Botany, Ohio Universityfor the use of laboratoryfacilities.This work was supportedin part by Natural Sciences and Engineering Research Council of Canada grantA-6908 and CentralResearchFund Grant, University of Alberta to R. A. Stockey. Literature cited Alvin, K. L., and M. C. Boulter. 1974. A controlledmethod of comparativestudyof taxodiaceouscuticles.J. Linn. Soc. Bot. 69:277-286. Buchholz,J. T., and N. E. Gray. 1948a. A taxonomic revision of Podocarpus.I. The sectionsof the genusand their subdivision with special referenceto leaf anatomy. J. Arnold Arbor. 29:49-63. 1948b. 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