Leptopus emicans (Dunn) 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

Vulnerable (VU B1a,b(iii)) (IUCN 2001). Extent of occurrence is below 20,000 km2 and the species is known from two areas only. Agricultural expansion is an increasing threat.

Distribution

East Himalaya and Burma.

Ecology

Riverine vegetation; altitude not known.

Morphology General Habit

Monoecious erect shrub, up to 3 m. Twigs longitudinally ribbed, glabrous, green brown

Morphology Leaves

Leaf blade elliptic, basally acute, sometimes rounded, apically acuminate to caudate, (3) 6 – 12 (13.5) × (1) 1.5 – 4 (4.6) cm, 2.5 – 3.5 times longer than wide, membranaceous, drying slightly discolorous brownish green, glabrous on both sides, margin glabrous, the caudex 10 – 15 mm long; midvein adaxially flat to prominent, abaxially prominent, secondary veins 8 – 10 pairs, adaxially flat to prominent, abaxially prominent

Morphology Leaves Petiole

Petiole 10 – 47 × 0.5 – 1 mm, ⅓ – ¼ of leaf blade length, glabrous

Morphology Leaves Stipules

Stipules deltoid, basally not auriculate, apically acute, translucent, c. 1 × 0.5 mm, glabrous, margin laciniate, glabrous

Morphology Reproductive morphology Flowers

Male and young female flowers not seen Female flowers 1 – 3 per fascicle, rotate

Morphology Reproductive morphology Flowers Calyx

Mature sepals 5, ovate to obovate, apically truncate to obtuse, 1 – 1.5 × 1 mm, 1-veined, glabrous outside, glabrous inside, margin erose, glabrous, eglandular Mature petals 5, obovate, apically rounded to emarginate, c. 0.3 × 0.2 mm, slightly shorter than disc, without veins, glabrous

Morphology Reproductive morphology Flowers Disc

Disc bilobed for ¾ of length, 0.4 – 0.8 × 0.2 – 0.3 mm, apically rounded, entire to erose, up to ⅓ of sepal length

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary 3 (4)-locular, glabrous; styles 3 (4), 0.6 – 0.8 mm long, free, glabrous; stigmas dilated

Morphology Reproductive morphology Flowers Pedicel

Fruiting pedicel 10 – 15 mm long Pedicel not articulate, glabrous Male pedicels articulate c. 0.6 mm above base

Morphology Reproductive morphology Fruits

Fruit 2.5 – 3 × 4 – 5 mm, strongly reticulate, glabrous, drying green Columella basally almost linear, widest at apex, 1.5 – 2 × c. 0.5 mm

Morphology Reproductive morphology Inflorescences

Male inflorescence axis 0 – 3 mm long

Morphology Reproductive morphology Inflorescences Bracts

Bracts as stipules

Morphology Reproductive morphology Seeds

Seeds reniform, 1.5 – 2 × 1 – 1.5 × 1 – 1.5 mm, with fleshy orange micropylar appendage up to 0.3 mm in diam., smooth to dimpled, brown

Morphology Reproductive morphology Seeds Embryo

Embryo with radicle slightly shorter than cotyledons

Note

This rare endemic taxon is aberrant in the genus Leptopus and possibly represents an independent lineage. Several gynoecium characters cause doubt as to its identity as Leptopus. Orange spongy tissue protrudes from the micropylar end of the seed, a character unique in tribe Poranthereae and extremely rare in Phyllanthaceae. The chalaza end of the seed is more strongly curved than that of other Leptopus species as the fruit is raised on a short fleshy stipe visible on dissection of a female flower. Apex of the columella is unusual with tissue protruding sideways, unlike the apically linear columella of other Leptopus species. The presence of apically wide emarginate petals has only been noted on poor quality material. Unfortunately no fresh material was available for DNA extraction and the few collections of this species lack good quality male and young female material.

Type

India, Arunachal Pradesh, Outer Abor Hills, Kobo, 6 Dec. 1911, Burkill 37068 (lectotype K! K000186357, selected here; isolectotype K!). The chosen lectotype is the only syntype sheet with seed as well as female material at various stages of fruit development.