Abutilon guineense, (Schumach.) Baker f. & Exell

Nimbalkar, Varsha Vilasrao & Sardesai, Milind Madhav, 2025, The Genus Abutilon (Malvaceae: Malvoideae) in India: A Taxonomic Revision and Insights from Micromorphology of Seeds, Systematic Botany (Basel, Switzerland) 49 (4), pp. 708-742 : 717

4. ABUTILON GUINEENSE (Schumach.) Baker f. & Exell in J. Bot. 74 (suppl.): 22. 1936.

Sida guineensis Schumach. in Beskr. Guin. Pl. 307. 1827.

A. indicum subsp. guineense (Schumach.) Borss. Waalk. in Blumea 14: 175. 1966.

A. indicum var. guineense (Schumach.) K. M. Feng in Fl. Yunnan 4: 28. 1982.

TYPE: GHANA, Thonning 38 [lectotype designated here: C-10004546 [photo]! . (http://www.daim.snm.ku. dk/digitized-type-collection-details?catno=C10004546) isolectotypes: C-10004545! C-10004548! C-10004549!]

Bushy shrub, less than 1 m high. Stem covered with dense stellate pubescence. Leaf lamina 4–15 ˟ 4–10 cm, pale green, ovate or orbicular, 7–9-nerved; apex acute. Petioles 3–10 cm long. Stipules lanceolate to triangular, apex acute, stellate pubescent. Flowers axillary, solitary; flowering pedicel 1–1.5 cm, articulated 2–3 mm below the flower; fruiting pedicel 5–10 cm long, articulated 1 cm below the fruit. Calyx pale green, campanulate or cup shaped, 1 cm across; calyx lobes 10–12 ˟ 4–6 mm, triangular, acute to acuminate, almost covering and exceeding the schizocarp in fruit. Corolla 2.5–3 cm across, yellow; petals ca. 12 ˟ 5 mm, broadly obovate, truncate or emarginate with unequal lobes at apex, glabrous. Staminal column 7–9 mm long, glabrous throughout, tube 2–3 mm long, filaments 4–5 mm long. Ovary ca. 4 ˟ 3 mm, globose, 20–25-loculed, ovules 3 per locule; stylar branches not exceeding staminal column, stigmas capitate. Schizocarps ca. 1.7 ˟ 1.2 cm, cylindrical, truncate, extremely velutinous with long armed stellate hairs. Mericarps 20–25, reniform, 10–12 ˟ 5 mm, flattened, rounded at base, acute at apex with short mucro, dorsally slightly curved, 3-seeded. Seeds 1.5–1.8 ˟ 1.8–2 mm, reniform, glabrous throughout, warted, dark brownish to black. Figures 4F–J , 5H–N .

Distribution and Habitat —The species is distributed in tropical and subtropical parts of Africa, Asia, and Australia. In India, it is reported from Andhra Pradesh, Rajasthan, Tamil Nadu, and Telangana ( Fig. 3 ). It grows in semi-arid regions, and occurs along dumping grounds and barren lands.

Etymology —The specific epithet guineense denotes the place Guinea, from where it is described.

Phenology —Flowering from August to January, sometimes extending up to February, and fruiting takes place from September to March.

Notes —Some Indian floristic studies ( Cooke 1903) listed the taxon as A. asiaticum (= Sida asiatica L.). Van Borssum Waalkes (1966) lowered this taxon to the subspecies level, as A. indicum subsp. guineense and synonymized the name ‘ A. asiaticum ’ under the subspecies. The treatment brought out the typification of S. asiatica by description (Van Borssom Waalkes 1966) which is not supported by the current code of ICN.

Borssum Waalkes’ s treatment of A. guineense as a subspecies of A. indicum is not applied in the present study, though it is followed in other Indian floristic works ( Sivarajan and Pradeep 1996; Paul and Nayar 1988; Paul 1993; Pullaiah and Chennaiah 1997; Pullaiah et al. 2002; Pullaiah and Rao 2002; Rao et al. 2001; Pullaiah 2015). The taxon is treated at species rank on account of the distinct characteristics such as plant less than 1 m, extremely villous fruits with more than 20 mericarps, and enormous difference of seed characters between A. indicum and A. guineense . Its sympatric occurrence with the main taxon A. indicum and other Abutilon species also validates the treatment of this at species rank. Therefore, it is treated here as ‘ A. guineense ,’ the combination made by Baker and Exell (1936). Use of the binomial ‘ A. asiaticum ’ for this plant is inappropriate ( Verdcourt 2003) and discussed in detail under A. indicum .

The name Abutilon guineense ( Sida guineensis Schumach. ) is lectotypified here by selecting the original material referred to in the protologue (Thonning 38, (C)). The specimens differ in having leaves with a triangular apex instead of rounded leaves with a short acute apex of the Indian population. The differing characters are treated here as a variation and the taxon is considered conspecific with the Indian population due to similarity in all other strong characters of fruit and seeds.

The individuals of this species can be confused with those of A. pannosum because of its villous appearance of fruits, but they can be distinguished from the latter by having a bushy habit with less than 1 m height, cylindrical fruits, and glabrous seeds.

Representative Specimens— India. — TAMIL NADU: Tiruchirapalli Dt., Tiruchirapalli , 1941, s.c. s.n., ( MH, labeled as A. asiaticum ) ; Tiruchirapalli, 16 Sep 2016, VVN 573 , 574 ( BAMU, SPPU). Coimbatore Dt., Ukkadam , 450 m, 28 Jan 1993, Sivarajan & Pradeep 45068 ( CALI) . South Africa. Kruger National Park , 17 Jan 1994, N. Zambatis 1997, PRE0805917 –0 ( PRE, photo!) . Tanzania. s.l., H. Leippert 6394, UBT0006564 ( UBT, photo!) . Togo. Kelegougan , 1973, J. F. Brunel 754, TOGO04357 ( TOGO, photo!) .

Figures

FIG. 4. Habit and morphology of A. fruticosum (A–E) and A. guineense (F–J). A, F. Habit and flower. B, G. Fruit. C, H. Dehiscing fruit. D, I. Mericarp. E, J. Seed.

FIG. 5. Line drawing illustration of A. fruticosum (A–G, drawn from VVN 548) and A. guineense (H–N, drawn from VVN 573). A, H. Leafy twig with flower and fruits. B, I. Flower. C, J. Staminal column. D, K. Gynoecium. E, L. Fruit. F, M. Mericarp. G, N. Seed.

FIG. 3. Distribution of A. australiense, A. bidentatum, A. fruticosum, and A. guineense in India.