Geranium nakaoanum

Description

Geranium nakaoanum is a Himalayan cranesbill known from Nepal, the Indian Himalaya, Bhutan and adjacent China, with around 61 GBIF occurrences reflecting its montane to alpine distribution. It occupies open alpine meadows, grassy slopes, streamsides and the herbaceous margins of dwarf rhododendron and juniper scrub on moist, humus-rich soils. The locality figured, Dur Tsachu in Bhutan at about 3800 m in June, sits within its typical band of roughly 3300-4500 m; the accompanying note of Pedicularis siphonantha at Dzongri in Sikkim at 4100 m in August underscores the high-elevation meadow community in which it grows, flowering through the monsoon summer.

It is a low, tufted perennial herb with a thickened rootstock, producing slender, often decumbent or ascending stems clothed in spreading or retrorse hairs. The leaves are long-petioled and palmately divided into five to seven deeply incised, lobed segments forming a rounded outline, the laminae sparsely hairy on both surfaces. The flowers are borne in few-flowered cymes on glandular-hairy pedicels; the five free petals are pink to rose-purple, frequently darker-veined and shallowly notched. Ten stamens surround the five-carpellate ovary, which matures into the characteristic beaked schizocarp whose mericarps spring apart elastically to disperse the seeds.

The species commemorates the Japanese botanist Sasuke Nakao, a participant in mid-twentieth-century Himalayan expeditions. It belongs to the large temperate genus Geranium, well represented in the Himalaya by several allied alpine taxa distinguished by indumentum, petal colour and leaf dissection. As a meadow perennial it contributes to the diverse alpine herb flora and is pollinated chiefly by bees and flies; no specific threat is recorded, though alpine grazing pressure can affect such populations.

Author: H.Hara · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of Nepal, Aedo monograph of Geranium, Yeo Hardy Geraniums