phek

. Vietnamosasa pusilla (A.Camus & Chavalier) Nguyen
Common name: Pai Pek; Pai Pet (Smitinand, 2001).
The Genus Vietnamosasa belongs to the family Poaceae, Tribe Bambuseae, Sub tribe
Racemobambosinae. Vietnamosasa pusilla (A.Camus & Chavalier) Nguyen was previously
classified as Arundinaria pusilla. After closer observation, it was granted its own genus along with
two other species, Vietnamosasa darlacensis Nguyen and Vietnamosasa ciliata (A. Camus &
Chavalier) Nguyen in 1990 (Nguyen, 1990).

V. pusilla can be found in shaded, mixed dipthocarp forests in eastern and northeastern Thailand as
well as Laos, Vietnam, and Cambodia. (Dransfield, 1996; Hacker, 1996) V. pusilla grows in soils
derived from sandstone and sandy loam. It has a pachymorph rhizome structure (clumping) that can
be found up to 20 cm in depth with short or long necks. Upright culms are light green when young
and grow to 50 cm in height. The culms are usually solid with a portion of the culm base located
below the surface. Distance between internodes is 20cm. Culms above ground are always straight.
V. pusilla also produces underground culms that grow horizontal to the surface and have buds at
each node which develop into single branches that emerge from below ground, usually after damage
to the main culm due to fire or drought. The underground culm does not have roots at each node.
Each node of the underground culm is 11 to 15mm long and may or may not be straight.
Vietnamosasa pusilla flowers regularly at the end of the rainy season. The flowers are borne on
leafless branches 10 to 50cm. in height. They emerge from a branch bud of the horizontal,
underground culm. Usually no more than 10 spikelets occur per branch with one or two spikelets per
node. Each spikelet is 8 cm long with 8-16 florets. A prophyll and a bracht bearing a bud are present
at the base of the spikelet. This pseudo spikelet is present in the inflorescence and distinguishes it
from the Racemobambos genera (Dransfield, 2000a).