Leptopus australis (Zoll. & Moritzi) Pojark.

Vorontsova, M.S. & Hoffmann, P. 2009. Revision of the genus Leptopus (Phyllanthaceae, Euphorbiaceae sensu lato). Kew Bulletin 64: 627. DOI: https://doi.org/10.1007/s12225-009-9155-x

Conservation

Least Concern (LC): extent of occurrence exceeds 20,000 km2.

Distribution

From Thailand, Andaman Islands and the Chinese Islands of Hainan, south to Sumatera, Java, and Timor, and east to the Philippines.

Ecology

Evergreen forest understorey on sand or limestone; 0 – 400 m.

Morphology General Habit

Herb to subshrub, ascendant to erect, monoecious, 0.1 – 0.5 m high

Morphology Leaves

Leaf blade ovate to lanceolate or obovate, basally long attenuate to acute, sometimes obtuse, apically obtuse to acute, (1.5) 2.5 – 7 (10) × (0.7) 1.2 – 2 (3.2) cm, 1 – 3.5 times longer than wide, membranaceous to thin chartaceous, drying discolorous to concolorous reddish to yellowish or greyish green, glabrous to hirsute adaxially, hirsute abaxially, margin hirsute; midvein adaxially flat, abaxially prominent, secondary veins 4 – 6 pairs, adaxially flat, abaxially flat to prominent

Morphology Leaves Petiole

Petiole 5 – 20 × 0.5 – 0.8 mm, ½ - ⅙ of leaf blade length, hirsute

Morphology Leaves Stipules

Stipules deltoid to subulate, basally not auriculate, apically acute, ferrugineous to almost black, 1 – 2.5 × 0.2 – 0.6 mm, glabrous to hirsute, margin entire, ciliate

Morphology Reproductive morphology Flowers

Female flowers 1 – 4 per fascicle, 2 – 4 × 3 – 6 mm, 3 – 4 times larger than male, rotate Male flowers 1 – 4 (rarely up to 6) per fascicle, 0.8 – 1.3 × 1.5 – 2.5 mm

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 5, 0.8 – 1.5 mm long; filaments 0.7 – 1.3 mm long; anthers 0.2 – 0.3 × 0.2 – 0.25 mm

Morphology Reproductive morphology Flowers Calyx

Sepals 5, ovate to obovate or oblong, apically acute to cuspidate, 1.5 – 3 × 1 – 2 mm, 0 – 3-veined, hirsute, margin entire, hirsute, eglandular Fruiting sepals accrescent to 2 – 6 × 1 – 3.5 mm Sepals 5, obovate to oblong, apically rounded, 1 – 1.6 × 0.6 – 1 mm, membranaceous, 0 – 3-veined, hirsute outside, glabrous inside, margin erose, glabrous to ciliate, eglandular

Morphology Reproductive morphology Flowers Corolla

Petals 5, linear to obovate, apically rounded, 0.1 – 0.5 × 0.1 – 0.2 mm, extending to ½ length of disc to slightly beyond disc, without veins, glabrous Petals 5, obovate to linear, apically rounded, 0.6 – 1.2 × 0.2 – 0.3 mm, ½ - ¾ of sepal length, membranaceous, 0 – 1-veined, glabrous on both sides, margin entire to erose, glabrous

Morphology Reproductive morphology Flowers Disc

Disc bilobed for ⅘ - ¾ of length, lobes apically truncate to acute, 0.7 – 1.2 × 0.1 – 0.2 mm, ⅔ as long to slightly shorter than sepals, slightly longer or shorter than petals Disc bilobed for ½ - ¾ of length, 0.3 – 0.8 × 0.2 – 0.4 mm, apically acute to truncate, erose or crenulate, up to ¼ of sepal length

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary 3-locular, densely hirsute; styles 3, 0.6 – 1 mm long, free, glabrous to basally hirsute; stigmas dilated to capitate

Morphology Reproductive morphology Flowers Gynoecium Pistillodes

Pistillode trilobed for ¼ of length or almost to base, 0.35 – 0.8 mm long, ¼ - ¾ of stamen length, glabrous

Morphology Reproductive morphology Flowers Pedicel

Pedicel 2 – 5 mm long, not articulate, hirsute Fruiting pedicel 5 – 9 mm long Pedicel 4 – 8 × less than 1.5 mm, articulate just above base, glabrous to hirsute

Morphology Reproductive morphology Fruits

Columella widest at base, apically linear, 1 – 1.5 × c. 0.5 mm Fruit 1.5 – 2 × 3 – 4.5 mm, smooth to faintly reticulate, hirsute, drying red brown to orange brown

Morphology Reproductive morphology Inflorescences

Inflorescences unisexual or bisexual, male inflorescence axis 0 – 3 mm long

Morphology Reproductive morphology Inflorescences Bracts

Bracts as stipules

Morphology Reproductive morphology Seeds

Seeds triquetrous, 1.2 – 1.9 × 1 – 1.5 × 1 – 1.5 mm, without appendages, transversely to irregularly ridged in the same seed, orange to brown

Morphology Reproductive morphology Seeds Embryo

Embryo with radicle as long as cotyledons or slightly longer

Morphology Twigs

Twigs terete to bilaterally flattened, hirsute, light green to brown

Note

The variable and widespread Leptopus australis can be immediately distinguished from other species of Leptopus by its smaller stature, dense indumentum, short female pedicels, small orange brown fruit and often attenuate leaf bases. L. australis and L. robinsonii are the only two species of Leptopus with deeply ridged seed. L. hirtus is a formal synonym of L. australis here for the first time, although this has been suggested in the past. Henderson (1939) stated that both Andrachne calcarea and A. hirta “appear to be merely forms” of L. australis. Airy Shaw (1964) tentatively agreed but eight years later (Airy Shaw 1971a publ. 1972) treated L. calcareus separately, noting that “it may be no more than a distinct ecotype” of L. australis. Van Welzen & Chayamarit (2007) treated L. calcareus as a synonym of L. australis.