REVISION OF AMORPHOPHALLUS BLUME EX DECNE . SECT . RHAPHIOPHALLUS ( SCHOTT ) ENGL . ( ARACEAE ) IN INDIA

The genus Amorphophallus Blume ex Decne. (Araceae), with more than 200 species, is one of the most taxonomically difficult genera of the family, and in fact is one of the moderately understood of all Asian aroid genera. The 11 sections recognised by Engler have been currently reduced to 10, and out of the 10 sections three, viz. Candarum Engl., Conophallus (Schott) Engl. and Rhaphiophallus (Schott) Engl. are represented in India. Rhaphiophallus as recognized now including sect. Synantherias comprises eight species: Amorphophallus bonaccordensis Sivad. & N. Mohanan, A. hohenackeri (Schott) Engl. & Gehrm., A. konkanensis Hett., S. R.Yadav & K. S. Patil, A. longiconnectivus Bogner, A. margaritifer (Roxb.) Kunth, A. mysorensis E. Barnes & C. E. C. Fisch., A. smithsonianus Sivad., and A. sylvaticus (Roxb.) Kunth. Herein A. bhandarensis S. R.Yadav, Kahalkar & Bhuskute is recognized at the new rank of variety, as A. mysorensis var. bhandarensis (S. R. Yadav, Kahalkar & Bhuskute ) Sivad. & Jaleel. The name Amorphophallus sylvaticus (Roxb.) Kunth is lectotypified here. All except A. sylvaticus (also occurring in Sri Lanka) are endemic to India.


Introduction
The genus Amorphophallus Blume ex Decne.(Araceae) is distributed in tropical Africa, Madagascar, tropical and subtropical Asia, the Malay Archipelago, Melanesia and Australasia (Mayo et al., 1997), and comprises in excess of 200 species.The species of Amorphophallus exhibit variation in shape and size of tuber, petiole, spathe, spadixappendix, and the individual female flowers (Hettersheid and Ittenbach, 1996).
Taxonomically and botanically it is one of the most difficult genera of the family due to various reasons including the timing of emergence of inflorescences and their relatively short active period of existence.The morphological similarity of the leaves of many species makes identification of the species with vegetative specimens difficult or impossible.Apart from these, the succulent and massive nature of the plant parts like tubers, petioles, peduncles and inflorescences, and the raphide contents in the plant body make collection and preservation of the specimens very difficult resulting in poor representation in Indian and International herbaria.
Amorphophallus was first placed in the tribe "Thomsonieae" (Blume, 1835;Bogner et al., 1985).Tribe "Thomsonieae" consisted of two closely related genera, Amorphophallus and Pseudodracontium.Several attempts have been made to reveal the phylogenetic relationships within the genus Amorphophallus sensu lato (incl.Pseudodracontium).Hetterscheid et al. (1994) have provided a fairly good discussion on the probable monophyly and character evolution in the then known species of Amorphophallus sect.Rhaphiophallus.
Molecular evidences indicated that the two genera could be merged into a single genus, Amorphophallus (Grob et al., 2002(Grob et al., , 2004)).A molecular study using a combination of matK and rbcL sequences revealed the position of Amorphophallus and other Araceae as a monophyletic clade in a basal node of the Order Alismatales (Tamura et al., 2004).The study of Araceae phylogeny by Cabrera et al. (2008) using a combination of matK, rbcL, the trnK intron, trnL intron, and the trnL-trnF spacer, showed the tribe "Thomsonieae" as a basal sister clade consisting of the tribes "Caladieae" and "Zomicarpeae".Sedayu et al. (2010) attempted to interpret morphological character evolution in Amorphophallus based on a combined nuclear and plastid phylogeny that is more completely sampled than in previous studies.Since Hooker's treatment of Amorphophallus (1893), several publications of ad hoc new taxa, rediscoveries, and reports of species new to India, e.g.Bogner et al. (1985), Sivadasan (1986Sivadasan ( , 1989)), Sivadasan et al. (1994), Hetterscheid et al. (1994), Bogner (1995), Hetterscheid and Sarker (1996), Sivadasan and Jaleel (1998a, b, 2000a, b, 2001, 2009) and Yadav et al. (2009) have greatly expanded our knowledge of the genus in India, but to date a full but a revision of the genus in India has yet to be undertaken.
Taxonomic History of Amorphophallus sect.Rhaphiophallus Engler (1911) in his monographic treatment of the family Araceae, treated the species presently recognized as belonging to the genus Amorphophallus under 3 genera, namely Amorphophallus Blume ex Decne., Plesmonium Schott and Thomsonia Wall., and recognized 11 sections under the genus Amorphophallus.Bogner et al. (1985) treated the genus Thomsonia as congeneric with Amorphophallus and also presented a detailed account of the characteristic features of Plesmonium margaritiferum and a plea for its treatment under the genus Amorphophallus by sinking Plesmonium under Amorphophallus.This was followed by the treatments by Sivadasan (1989), Hetterscheid et al. (1994), Hetterscsheid and de Sarker (1996), Sivadasan et al. (1994) and Mayo et al. (1997) wherein Plesmonium has been recognized as congeneric with Amorphophallus.With the merger of Amorphophallus sect.Synantherias with sect.Rhaphiophallus (Sivadasan, 1989), the number of sections as recognized by Engler (1911) has been reduced to 10, and now in India the genus is represented by 3 sections, viz.Candarum Engl., Conophallus (Schott) Engl.and Rhaphiophallus (Schott) Engl.
The present article is limited to revision of Amorphophallus sect.Rhaphiophallus (Schott) Engl., the largest section of the genus in India, and characterized by having a staminodial zone between the male and female zones on the spadix.

Methodology
Intensive and extensive field explorations were made all over India including the Andaman and Nicobar Islands.Repeated collection trips during different seasons were essential to get the taxa both in reproductive and vegetative phases.All relevant data about the plants have been recorded in a field book.Photographs were taken, and collected a sufficient number of plants based on the population, for making herbarium specimens.Herbarium specimens were prepared following the wet method (Fosberg and Sachet, 1965).Tubers were collected and cultivated in Calicut University Botanical Garden for future observations and studies.Illustrations were made and camera lucida was used wherever necessary.Specimens, especially nomenclatural types at major Indian and international herbaria were examined.

Key to the
Phenology: Flowering: April; fruiting may be in May, but fruiting specimens have not so far been collected.Distribution: So far known only from the type locality.
Notes: Amorphophallus bonaccordensis differs from all other species by the ovateoblong spathe with a prominent basal convolute tubular portion separated from the oblong erect limb by a slight constriction.The spadix appendix is cylindric with a rounded tip and is much shorter than the spathe.Amorphophallus bonaccordensis closely resembles A. hohenackeri in its general morphological features.(Fig. 2) Type: India, Karnataka State, Mangalore, Canara, R.F.Hohenacker 21646 (B).
Phenology: Flowering: March-May; fruiting: May-August.Distribution: Very limited in distribution, known only from Kerala and Karnataka states.Notes: Amorphophallus hohenackeri differs from other species in the nature of the spathe.It is closely related to A. bonaccordensis but it differs in having a spadix shorter than the spathe, a barren zone below the sterile and female flower zones, and a more or less cylindric spadix appendix without terminal tapering.
Distribution: Restricted to Goa and Maharashtra states.
Notes: Amorphophallus konkanensis differs from other species in having the completely convolute spathe with maroon inside and the spadix with rhomboid, slightly convex neuter flowers with whitish, dark purple or faint purplish hue.
Distribution: So far known to occur only in Piparia, Madhya Pradesh state.
Notes: Amorphophallus longiconnectivus Bogner has been rediscovered (Sivadasan and Jaleel, 1998) at its type locality in Madhya Pradesh, for the first time since Haines's original gathering in 1910.Amorphophallus longiconnectivus is unique in various aspects and is highly variable in its spadix structure.Usually the spadix has a stipe, followed by a zone of female flowers, a staminodial zone, a zone of male flowers, an upper sterile flower zone, and a spadix appendix with a stipe.But variations from the typical condition have also been noted.In some specimens the spadix appendix is completely lacking.In some, both basal staminodial zone and spadix appendix are lacking, but this condition is very rare or may be abnormal.Variations in morphology and size of other floral organs such as connectives of male flowers, neuter flowers and spadix appendix are also noticed.
Tubers more or less sub-globose to depressed globose, 2.5-5.0 cm diam.and 1.8-3.5 cm thick in vegetative phase, 7-13 cm diam.and 5.0-6.5 cm thick in reproductive phase, seasonally producing numerous small globose to fusiform offsets, varying from 7-11 per tuber, each 5-7 mm diam.and 8-14 mm long; skin pale brown to yellowish brown.Petiole smooth, 24-84 cm long, 1.0-3.3cm diam.at base; green with numerous narrowly elongated black-margined pale green stripes, with small spots between, petiole paler towards the tip, dark green to blackish green at the extreme base.Lamina 32-76 cm diam., the primary rachises smooth, and coloured as for petiole, 3-9 cm long, 4-12 mm diam., leaflets linear to lanceolate, 8-24 cm long, 1.1-3.5 cm broad, decurrent at base, upper surface green, paler below.Peduncle smooth, 50-70 cm long, 2-4 cm diam., colour same as that of the petiole.Spathe broader than long, broadly ovate or broadly triangular, 11.0-17.5 cm long, 13-20 cm broad, tip acute, not differentiated into basal tube and upper limb; pale greenish outside, pale purplish within, dark purplish, prominently verrucate at base within.Spadix as long as or slightly longer than the spathe, 14-20 cm long, lacking a sterile appendix; stipe 6-11 mm, greenish; female zone 1.1-2.8cm long, 9-18 mm diam.; staminodial zone 2.0-3.5 cm long; male zone elongate-conoidal, 6-9 cm long, 1.0-1.5 cm diam.at base.Female flowers: each 5-6 mm high, ovary pale green, slightly broader than stigma, 2.5-3.0 mm long, c. 2.5 mm diam., 2-locular; style very short, 0. Notes: Amorphophallus margaritifer resembles A. longiconnectivus in its general appearance of greenish spathe that is not differentiated into tube and limb, and the nature of the spadix.But the former differs from the latter in having large elongate-obovoid, cream-coloured neuter flowers, and the lack of a spadix-appendix.A. longiconnectivus has a short stipitate appendix and in some cases the appendix bears irregularly formed structures, some of which resemble rudimentary sterile male or female flowers; and the neuter flowers are greenish, short, stout and subulate.Rarely in some of the specimens of A. longiconnectivus the neuter flowers and spadix-appendix are lacking and hence there might be a chance of gradual reduction in appendix size and its complete absence.

Key to the varieties of A. mysorensis
1. Spathe dull purplish; neuter flowers globose, brownish red; spadix appendix dark purplish, inconspicuously irregularly furrowed at base, smooth above, tip blunt, c. 8.5 cm long.var.mysorensis -Spathe brownish-pale green with vertical prominent veins; neuter flowers rhomboid-conical with usually purplish apex; spadix appendix pale yellow, with irregular furrows and small protuberances, tip pointed, 3.5-4.0cm long var.bhandarensis Amorphophallus mysorensis E. Barnes & C. E. C. Fisch., Bull. Misc. Inform. 10: 661 (1939).var.mysorensis (Fig. 6) Tubers normally depressed globose, 2.5-9.0 cm in diam.and 2-5 cm thick in vegetative phase; c. 8.5 cm diam.and 3 cm thick in flowering phase, skin creamcoloured.Petiole smooth, 37.5-54.0cm long, 0.5-1.5 cm diam.at base, slightly tapering to the tip, pale greenish with dark olive-green and brownish-black mottling, paler towards the tip, extreme base whitish or pale pink in colour; leaflets sessile, linear-lanceolate, large leaflets 9.0-18.5 cm long and c. 1.8 cm broad, small leaflets 1.8-4.0cm long and c. 8 mm broad, acuminate at apex and decurrent at base, light green above and paler below, lateral nerves 7-11 pairs.Peduncle slender, smooth, c. 63 cm long, and c. 1 cm diam.at base, identical with petiole in colour and pattern of mottling.Spathe broadlyovate, c. 12.5 cm long, and c. 12 cm broad; tip acute, fully convolute, c. 4.5 cm diam.at base and 3.7 cm diam.at top just below the mouth; mouth dilated, 4.8 cm diam., not differentiated into a tube and limb; dull purplish outside with numerous fine, raised parallel veins; inside purplish at top, dark purplish and verrucose at base.Spadix longer than the spathe, c. 18 cm long with a stipe of c. 6 mm long and 12 mm diam.; female zone c. 2 cm long and 1.2 cm diam., male zone c. 5.8 cm long and 1 cm diam., staminodial zone c. 1 cm long, terminal sterile appendix of c. 8.5 cm long, and 7 mm diam.at base, narrowed to the tip.Female flowers: ovary spherical, c. 2 mm diam., yellowish-green, 2-4-locular; stigma 2-4-lobed, pale yellow in colour.Neuter flowers closely arranged, each flower spherical, brownish-red, glossy, c. 6 mm diam.Male flowers: each c. 1.8 mm long, c. 1.5 mm broad, 4-celled, opening by 2 apical elongated pores, yellowish flushed with red at top along the connective.Spadix appendix c. 8.5 cm long, cylindrical, tapering towards the tip, dark purplish, inconspicuously irregularly furrowed at the base, smooth above, becoming warty and wrinkled after anthesis.Infructescence not observed.
Phenology: Flowering: March-April; fruiting specimens have not been observed, fruiting may be during May-June.
Distribution: Known only from the type locality.
Phenology: Flowering and fruiting: July-August.Distribution: Known only from the type locality.Notes: Amorphophallus bhandarensis was published recently (Yadav et al., 2009) during the preparation of the present article, the description is primarily based on the protologue of the species.A thorough study of the characteristic features of the species revealed that although it exhibits similarities with A. konkanensis, A. mysorensis and A. sylvaticus, it mostly resembles A. mysorensis in several morphological features including the general shape of spathe and spadix.The shape of neuter flowers and length of the spadix appendix are stated as being different from those of A. mysorensis by Yadav et al. (2009).The neuter flowers usually exhibit variation in their shape and colour.Even though the spadix appendix also exhibits variation in length, the relatively short sized appendix of the species is a striking character.However, gross morphological similarities among the two species indicate the close relationship between the two and hence A. bhandarensis deserves only the status of a variety of A. mysorensis which is herein treated accordingly.
Tubers compressed-globose or irregularly sub-globose, 2.5-4.0 cm diam.and 1.8-2.3cm thick in vegetative phase; 4-6 cm diam.and 2.8-3.5 cm thick in reproductive phase; skin smooth, glossy.Petiole smooth, 25-55 cm long and 1.0-1.7 cm diam.at base; green with white specks and mottles, extreme base whitish and apical portion green, basally surrounded by 4-6 cataphylls, each cataphyll 8-11 cm long and 2.2-3.0 cm broad, tip acute with a stiff projection terminating in bifid apex, pale pinkish.Lamina 30-40 cm diam., leaflets obovate-oblong, 3.5-13.8cm long and 1.5-4.5 cm broad, apex acuminate, lower surface pale green, margin erose, glossy, venation closely pinnate.Peduncle smooth, 9.0-10.5 cm long and 6-7 mm diam.at the base, colour same as that of the petiole surrounded by 4-6 cataphylls.Spathe funnel-shaped, broadly obovate when spread with round or obtuse base, apex entire or notched, 4.0-4.5 cm long and 4.5-5.0cm broad, basally convolute with broadened mouth, pale green with minute purplish specks outside, dark purplish with minute truncate projections at the base within for about one third of the length, pale yellowish green or creamy and smooth above.Spadix sessile, c. 4 times longer than the spathe; female zone 6-9 mm long; staminodial zone 5-6 mm long, followed by a male zone of 2.0-2.2cm long, and a terminal sterile appendix.Female flowers: each with ovary c. 1.5 mm high and c. 2 mm diam., cream-coloured; style very short c. 0.5 mm long; stigma sub-equalling the ovary in diameter with 3-5 stout echinations, pale green becoming cream in colour after anthesis.Neuter flowers in 2-5 rows, each obovoid or ellipsoid, dark-purplish or sometimes pale green, c. 5 mm high and c. 3 mm diam., becoming shrunken and thin at maturity.Male flowers: each 1.0-1.3mm high and 1.5-1.8mm broad, sub-rectangular in outline with rounded corners, creamcoloured or pale greenish to yellowish-green with pale purplish tinge at the top, dehiscence by apical confluent pores.Spadix appendix 12.5-21.0cm long, c. 8 mm diam.at the base and tapering to the tip, bent or hanging from the middle, dark purplish, tip sometimes purplish green, with irregular longitudinal shallow furrows and few small spinescent projections at the base.
Tubers depressed sub-globose, 3-5 cm diam.and 1.5-3.0cm thick in vegetative phase; 5-6 cm diam.and 3-4 cm in thick in reproductive phase; skin smooth, whitish or cream-coloured; roots numerous, 6-12 cm long and c. 0.1 cm diam.Petiole smooth, 31-65 cm long and 0.5-1.5 cm diam.at the base, greenish with pale green ovate-elongate irregular blotches with white margin, or pale green with pale yellowish ovate-elongate blotches, or pale green with whitish blotches, or light brown with pale brown blotches, and in all with minute mottling in between the blotches.Lamina 32-60 cm diam., leaflets glabrous, ovate-elliptic, lanceolate or linear lanceolate, 4.0-7.5 cm long and 2.5-3.5 cm broad, decurrent at the base, tip acute, or acuminate in the case of linear lanceolate leaflets, ventral side pale green, margin slightly undulate.Peduncle smooth, 40-50 cm long and c. 1 cm diam.at the base, identical with petiole in colour and pattern of blotches.Spathe ovate, 3.0-5.5 cm long and 4.0-6.5 cm broad, completely convolute and open at the top; pale pinkish or greenish-purple outside, purple and verrucose within.Spadix 5-6 times than the spathe, 14-22 cm long; stipitate; stipe 3-5 mm long, pale greenish; female zone 0.8-1.2cm long, staminodial zone 4-8 mm long; male zone 1.6-3.0cm long; terminal spadix appendix c. 18 cm long and 6-9 mm diam.at the base.Female flowers: each with ovary sub-globose, c. 2 mm long and c. 2 mm diam., 2-locular with representatives then known of sect.Rhaphiophallus, are also listed.Fischer (1931) in Gamble's 'Flora of the Presidency of Madras' described six species of which A. hohenackeri, Plesmonium margaritiferum (= A. margaritifer) and A. sylvaticus are the ones representing Amorphophallus sect.Rhaphiophallus.After the publication of the important works of Hooker (1893), Engler (1911) and Fischer (1931) A. mysorensis var.mysorensis has been rediscovered during the course of the present investigation after about 60 years of its first collection in 1939 by Barnes. A. longiconnectivus was described by Bogner (1995) based on a single specimen collected by Haines in the year 1910 and available at the Kew herbarium (K).No other earlier or later collections are known to be available in any Indian or foreign herbaria other than the collections made during the present investigation which formed the second collection of the species after 87 years of its first collection.
, a total of six new taxa, viz. A. bhandarensis S. R.Yadav et al. (= A. mysorensis var.bhandarensis (S.R.  Yadav et al.) Sivad.etJaleel, A. bonaccordensis, A. longiconnectivus, A. konkanensis,  A. mysorensis and A. smithsonianusbelonging to this section have been published, thereby enhancing the total number of taxa of this section in India to nine.The endemic taxa with very restricted distribution confined to one State alone are A. bonaccordensis (Kerala), A. longiconnectivus (Madhya Pradesh), A. mysorensis (Karnataka), A. mysorensis var.bhandarensis (Maharashtra), and A. smithsonianus (Kerala).Amorphophallus hohenackeri occurs in Kerala and Karnataka states, and A. konkanensis in Goa and Maharashtra states.A. margaritifer and A. sylvaticus are the species having wider distribution in the country with the latter having extended distribution outside India occurring in Sri Lanka.