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Chamaesium H.Wolff
Mark F. Watson
Royal Botanic Garden Edinburgh

Glabrous biennial or perennial herbs, base often surrounded by papery leaf remains. Leaves pinnate; pinnae suborbicular to elliptic, shallowly lobed or crenate. Umbels compound; bracts leaf-like; umbellules small, rays unequal; bracteoles in Bhutanese species leaf-like or linear. Calyx teeth minute triangular or obsolete. Petals obovate, incurved at apex. Stylopodium a flattened dome, dark purple, forming a characteristic thickened rim with the top of the ovary/fruit, rim wider than the ovary and young fruit, and about as wide as the mature fruit. Fruit oblong-ovoid, laterally compressed, mericarps sub-terete, characteristically 10-ribbed, ribs green, furrows brown.

Key to species
1 Plants acaulous or with a short stem >5mm thick C. novem-jugum
+ Plants 10–20cm tall, with slender stems <5cm thick C. viridiflorum

Chamaesium novem-jugum (C.B.Clarke) C.Norman
    Trachydium novem-jugum C.B.Clarke
Subacaulous herbs, rarely with a short 0.5–1cm thick stem, 2-10cm tall; tap-root short and thick. Leaves mainly basal, shiny green above, 3–11 x 1.5–3.5cm (including petiole); leaflets in 3–5 pairs, ovate or suborbicular,5–20 x 5–17mm, acute or rounded, base rounded, nearly sessile, margin minutely crenate-toothed. Umbels 7–20-rayed; rays 2–13cm, rather stout; bracts few, early deciduous; umbellules 13–25-flowered, 0.8–1.5cm across; pedicels 2–7mm; bracteoles 5–6mm, linear or 3-lobed with narrow segments. Petals green or tinged purple, c 1.5mm. Fruits 2.5–3 x 2–3mm, ribs in young fruit wavy.

Bhutan: C—Thimphu district (Nya Tsho, Phajoding, Paga La to Lawgu); N—Upper Mo Chu district (Chomp Lhari, Guile La, Laya, Pya La) and Upper Pho Chu district (Chojo Dzong).
Chumbi: Yak La.
Sikkim: Kongra La, Phaklung, Thagia, Yumthang.

World Distribution: E Himalaya to SW China. 

Ecology: Moist or wet, semi-open habitats, rocky areas, moorland, Rhododendron scrub. 3050–4900m.
Flowers July–September.

Illustration [Fig. 50 a-c]

Specimen List [3576]

Chamaesium viridiflorum (A.R.Franchet) R.H.Shan
    Trachydium viridiflorum A.R.Franchet
    Trachydium affine W.W.Smith.
Similar to C. novem-jugum but slender-stemmed (2–3mm thick) 6–28cm tall; leaves cauline, 4–12 x 1.2–2cm (including petiole); leaflets in 2–3 pairs, elliptic or ovate c 10 x 5mm, obtusely shallowly lobed; umbels 4–6-rayed; rays slender, 1.5–3cm long; bracts narrowly pinnatisect 1.5–2.5 x 0.7–1cm; umbellulesc 1.5cm across; bracteoles pinnatisect 7–10mm. Mature fruit unknown.

Sikkim: Ningbil (Chola Range).

World Distribution: E Himalaya to SW China 

Ecology: 4110–4265m.
Flowers August.

Specimen List [3578]

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