Proc. Indian Acad. Sci. (Plant Sci,), Vol. 100, No. i, February 1990. pp. 61-69. Printed in India. Fruit and seed structure in Araceae A R KULKARNI, D DOSI and V M MANOJ Department of Life Science, University of Bombay, Santacruz (East), Bombay 400098, India MS received 27 December 1988; revised 21 November 1989 Abstraet. Fruit and seed anatomy of 12 species of Araceae distributed in 11 genera has been described. Taxonomic significance of fruit and seed anatomy has been brought out. Keywords. Fruit; seed; anatomy; Araceae. 1. Introduetion Our knowledge of fruit and seed structure in Araceae is quite meagre (Netolitzky 1926). Windle (1889) recorded the occurrence of fibres (trichosclereids) and raphides in the fruits of Monstera. Buell (1935) stated that the seeds of Acorus are ensheathed by hard transparent mucilage that rapidly absorbs moisture and swells into gelatinous mass when wetted. The present study, mainly aimed at recognising taxonomic significance, describes anatomy of mature fruits and seeds of 12 species of 11 genera in Araceae. 2. Materials and methods Mature fruits and seeds of Pistia stratiotes and Aglaonema cornmutatum were collected from ptants cultivated in gardens of Ruia College, Bombay and those of other species from forests of various places in Maharashtra and fixed in FAA. Custo- mary procedure of dehydration, embedding and sectioning was folIowed. The microtome sections of 20-30/zm thickness were stained with 1% safranin in 70% alcohol and 0.5% aniline blue in absolute alcohol. 3. Results Fruits in Araceae are raphidian berries. Amongst the species examined, they are of composite type in Cryptocoryne and simple in others. The simple ones are all unilocular. The pericarp is thin and parenchymatous. It includes raphide sacs, vascular strands devoid of fibrous sheath and, occasionally the pigmented/tannin cells and druses. The seeds are ribbed/nonribbed. The testa is massive with compactly arranged parenchymatous cells containing raphide sacs, some times pigmented cells, rarely sclerotic elements. The tegmen is thin and tanniniferous or is reduced to a layer of cuticle. The endosperm is starchy with outermost aleurone layer. Embryo is well developed, rarely adventitious and the endosperm like tissue containing raphide sacs. 61 62 A R Kulkarni, D Dosi and V M Manoj Subfamily: Lasioideae Tribe: Pythonieae Amorphophallus commutatus Engler Fruit: Ovoid, one seeded; stigmatic remains apical; seed coat buff coloured. Fruit wall 10-12 layered in width (figure 9). Outer and inner epidermal cells rectangular, tangentially arranged with a thin layer of cuticle on the outer walls. Ground tissue of polygonal to oval, radially elongated, loosely arranged cells. Raphide sacs few. Vascular strands in a single ring (figure 13) situated in the inne4.. part of fruit wall. Seed: Seed coat epidermis highly cutinised, followed by 3-4 layers of p0lygol~a 1, some pigmented cells; innermost layer phellogen !q233 9). The ground tissue Of polygonal cells with simple c!rr starch grains and conspi.ct~aus, clrcu!ar r0phide sacs (figure 9). Adventitious shoot bud welldifferentiated with lateral roots. Subfamily: Philodendroideae Tribe: Aglaonemateae A91aonema commutatum Schott Fruit: Ovoid, one seeded, stigmatic remains, terminal. Seeds ovoid, seed coat buff coloured. Fruit wall 15-20 layered. Outer and inner epidermal cells tubular to rectangular, tangentially oriented, cutinised with a layer of cuticle on outer face. Ground tissue cells oval to polygonal (figure 12). Raphide sacs many, of similar size as ground parenchyma cells. Vascular strands in a ring, situated towards inner side of fruit wall (figure 12). Seed: Seed coat with highly cutinised epidermal cells followed by 4-5 rows of phellogen like layers (figure 12). Ground tissue cells polygonal, dense!y filled with simple circular starch grains; raphide sacs common. Adventitious shoot bud well developed with lateral roots. Subfamily: Colocasioideae Tribe: Colocasieae Subtribe: Steudnerinae Gonatanthus sarmentosus Klotzsch Fruit: Small, many seeded, irregularly lobod, closely arranged around the fruiting axis. Fruit wall 10-12 layered. Epidermal eells tubular to rectangular, tangentially oriented with cutinised walls anda layer of cuticle on outer face. Ground tissue cells polygonal, densely filled with starch grains (figure 10). Raphide sacs occasional, large, circular. Vascular strands inconspicuous. Seed (figure 10): Testa compressed, 4-5 layered, wider around micropyle, cells rectangular thin walled; raphide sacs in a ring, crowded in micropylar area. Tegmen two layered, cells rectangular, narrow, highly sclerified, filled with brown content. Fruit and seed structure in Araceae 63 Endosperm with peripheral layer of aleurone cells, filled with dense cytoplasm having granular contents; inner cells polygonal, thin walled, densely filled with simple starch grains having excentric hilum; embryo well developed. Tribe: Ariopsieae Ariopsis peltata Nimmo Fruit: Berries sessile, partly adnate to the inflorescence axis, obl0ng, :t:angled, unilocular, many seeded. Seeds elongated, strongly longitudinally ribbed (figure 1); ribs supported by multilayered sclerotic cells. Endosperm starchy, embryo apical. Fruit wall 7-12 layered in width (figures 1, 2). Epidermal cells outer tubular, inner oval, tangentially arranged, with a thin layer of cuticle. Ground tissue of oval- circular cells; inner-most 2-3 layers densely filled with starch grains. Vascular strands few, restricted to inner part of fruit wall (figure 2). Raphide sacs frequent in outer part of fruit wall. Seed: Testa massive, lobed, each lobe internally supported by regularly arranged longitudinal sclerotic ribs alternating with parenchymatous tissue (figure 2). Outer epidermis wavy, of squarish cells; inner epidermis highly cutinised of rectangular cells. Ground tissue reduced, with a ring of oval to circular raphide sacs situated towards inner side. The ribs appear to be continuous in basal funicle also. Tegmen reduced, of 1-2 rows of radially compressed, tangentially arranged rectangular cells filled with coloured material, with thick uniform layer of cuticle on outer face (figures 1, 2). Endosperm starchy, cells polygonal, starch grains simple, circular. Embryo well developed. Subfamily: Aroideae Tribe: Areae Subtribe: Arinae Sauromatum pedatum (Willd) Schott Fruit: FrUitlets densely arranged on the inflorescence axis, with flattened apical surface having persistant stigmatic residue in center, lateral sides 3-5-gonous; seeds 1-3 (figure 14), mostly one, erect, elongated; seed coat with starch filled testa, and brown tegmen (figure 11), embryo opical. Fruit wall: Epidermis of cutinised cells; outer epidermal cells polygonal in surface view, rectangular in transectional view; inner epidermal cells hexagonal and longitudinally oriented in surface view, rectangular in transection and tangentially extended. Vascular strands small, in a ring towards inner side of fruit wall (figure 14). Ground tissue cells with numerous starch grains. Raphide sacs numerous, polygonal to circular. Seed: Testa and tegmen free right to the base; testa broader at base and at micropylar apex, 8-10 layered in the middle, outer epidermal cells enlarged, tubular to rectangular, free of starch; inner epidermal cells small, squarish. Ground tissue cells hexagonal, longitudinally extended, filled with starch grains (figure 11); raphide sacs ovoid, common specially at base and apex (figure 14). Tegmen closely adhering the seed surface, 1-2 layered (figure l l) but broader at micropylar and chalazal 64 A R Kulkarni, D Dosi and ~" M Manoj v . 9 9 Figures 1-12. TS of fruit wall and seed. 1 and 2. Ariopsis peltata. 1. Fruit wall and seed ( x 150). 2. Sector enlarged ( x 300). 3. Cryptocoryne spiralis. Sector of fruit ( x 300). 4 and 5. Pistia stratiotes. 4. Gross view ( x 75). 5. Sector of the fruit ( x 300). 6. Lage- nandra ovata. Sector of fruit ( x 300). 7. Theriophonum indicum. Fruit wall along with seed (x 75). 8. Arisaema tortuosum. Sector of fruit (x 300). 9. Amorphophallus commutatus. Fruit sector (x 300). 10. Gonatanthus sarmentosus. Fruit wall and seed (x 300). ll. Sauromatum pedatum. Fruit wall and seed {x 150). 12. Aglaonema commutatum. Inner part of fruit wall and seed { x 300). (Vt, Vascular strands; emb, embryo; Sec, seed coat; d, druses; Fw, fruit wall). Fruit and seed structure in Araceae 65 O 9 Vt emb~/~'17 rs 18 Figures 13--21. TS of fruit wall and seed. 13. Amorphophallus commutatus. Fruit (x 8). 14. Sauromatum pedatum. Fruit (x 8). 15. Arisaema tortuosum. Fruit (x 8). 16. Crypto- coryne spiralis. Gross view of fruit in LS (x 8). 17. Pistia stratiotes. Fruit (x 20). 18. Cryptocoryne spiralis. Gross view of fruit in TS (x 8). 19-21. Typhonium cuspidatum. Fruit in gross view. 19. TS ( x 8). 20. LS ( x 8). 21. Sector of fruit wall ( x 100). (rs, Raphide sac; Vt, vascular strands; emb, embryo; fw, fruit wall). 66 A R Kulkarni, D Dosi and V M Manoj ends; cells tubular, pigmented witla cutinised walls. Endosperm cells squarish to polygonal, thin walled (figure 11), densely filled with simple or compound, variously shaped, many times irregularly angled starch grains with prominent central hilum. Peripheral aleurone layer prominent. Theriophonum indicum Schott Fruit: Unilocular, 4-5 seeded, seeds globose or vaguely lobed. Fruit wall: About 10 layered in radial extent (figure 7). Outer and inner epidermal cells rectangular, radially oriented. Ground tissue with a ring of vascular strands situated in the mid part of fruit wall. Raphide sacs circular,