Abutilon australiense

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 : 711

1. ABUTILON AUSTRALIENSE (Hochr. ex-Britten) Nimbalkar, Nandikar et Sardesai, Phytotaxa 413 (3): 251–256. 2019. A. indicum var. australiense Hochr. ex Britten, Illustrations of the Botany of Captain Cook’ s Voyage Round the World, 1. t. 19. 1900. A. asiaticum var. australiense (Hochr. ex Britten) Fosberg, 1966 . Micronesica 2: 150. 1966. TYPE: t.19, Illustrations of the Botany of Captain Cook’ s Voyage Round the World, 1900. [lectotype: designated by Nimbalkar et al. 2019b].

Abutilon indicum subsp. albescens (Miq.) Borss. Waalk. var. australiense Borss. Waalk., Blumea 14: 173, f. 19c (1966) nom. illeg. A. indicum subsp. albescens (Miq.) Borss. Waalk. var. australiense Borss. Waalk., Blumea 14: 173, f. 19c. 1966. nom. illeg.

Shrubs, 2– 3 m. Stem with light brown bark, young stem with pubescence of short stellate hairs intermixed with simple hairs. Leaf lamina 5–15 3 5–10 cm, light green, ovate or orbicular, 5–7 palmately nerved apex acute; margin coarse to serrate in young leaves, subentire in mature; stellate pubescent on adaxial and abaxial surfaces. Petioles 4–10 cm long. Flowers axillary, solitary; flowering pedicels 2–3 cm, articulated 5 mm below the flower; fruiting pedicels 3–6 cm long, articulated 1 cm below the fruit. Calyx pale green, campanulate, 1.5–1.7 cm across, calyx lobes 4–5 3 10–12 mm, gradually tapering towards the end, as long as or exceeding the fruit. Corolla 3 cm across, yellow; petals 3–5 3 13–15 mm, broadly obovate, apex truncate or slightly lobed or emarginate, glandular hairs on apical margins and towards adjacent petal, base stellate pubescent. Staminal column 6–10 mm long; base stellate pubescent; tube 4–5 mm long, glabrous; filaments 4–5 mm, glabrous. Carpels 13–15; ovary 3–4 3 3 mm, globose, 2–3 ovules per carpel; stylar branches glabrous, exceeding the puff of filaments; stigmas yellowish, capitate. Schizocarps 1.5 3 1 cm, globular, indented at apex, brownish on maturity. Mericarps reniform, 13 3 5 mm, base rounded, apex slightly tapering with mucro, dorsally curved, each 3-seeded. Seeds, 2–2.5 3 2 mm, reniform, densely pubescent with simple hairs, glabrous at hilum, surface brownish, warted. Figures 1A–E , 2A–G .

Distribution and Habitat — A. australiense is distributed in Australia, Malaysia, New Caledonia, and India. In India, it is reported from the Krishna River bank at Nagarjunsagar in Telangana state ( Fig. 3 ). The plants grow in loamy soil along the riverbank ( Nimbalkar et al. 2019b).

Etymology —The specific epithet australiense comes from the name of the continent Australia from where it was first described as a variety.

Phenology —Flowers from July to December; fruiting begins in September and ends in January.

Notes —The plant was first described as a variety of A. indicum ( Britten 1900) . Later, it was treated under A. indicum subsp. albescens by Van Borssum Waalkes (1966). The infraspecific classification was followed in subsequent Indian floristic studies. However, its sympatric occurrence with the main species A. indicum and other Abutilon species viz., A. hirtum and A. bidentatum disallows its treatment under

subspecies. It is also worthy of its position at a species rank on account of its distinct morphological characters ( Nimbalkar et al. 2019b).

Additional Specimens Examined— India. — TELANGANA: Nalgonda Dt., Krishna Riverbank ; 24 Dec 2017, VVN 597 , ( BAMU, SPPU) . Indonesia. Timor Laut , s.d, H. O. Forbes 3330, ( A 00052680 [photo!]) ; Timor , H. O. Forbes 3330, ( K 000659525 [photo!]) ; Lesser Sunda Islands, Timor , H. O. Forbes s.n., ( L 0012914 photo!) ( L) ; s.l., s.d., H. O. Forbes s. n. ( BM 000554245 [photo!]) New Caledonia. s.l., 1860, Gilliwray s.n. ( G 00353079 [photo!]) ; s.l., s.d., s.c. s.n., ( G 00353085 [photo!]) .

Figures

FIG. 1. Habit and morphology of A. australiense (A–E) and A. bidentatum (F-J). A, F. Habit and flower. B, G. Fruit. C, H. Dehiscing fruit. D, I. Mericarp. E, J. Seed.

FIG. 2. Line drawing illustration of A. australiense (A–G, drawn from VVN 597) and A. bidentatum (H–N, drawn from VVN 505). 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.