POACEAE Tribe BAMBUSEAE
Shrubs or trees, very rarely perennial herbs, arising from underground rhizomes; culms erect or sometimes climbing, 0.545 m high or rarely more, bearing sheaths with reduced blades. Leaf-blades flat, usually linear to oblong-lanceolate, many-nerved with transverse connections, mostly with a false petiole which is articulated with the sheath; ligule short, scarious. Inflorescence a panicle or raceme, the spikelets often aggregated into dense clusters. Spikelets all alike, 1-manyflowered, usually disarticulating below the lemmas at maturity, the rhachilla prolonged or not; glumes commonly 2, sometimes more and then grading indistinctly into lemmas, often with secondary spikelets in their axils from which a complex cluster is built up; lemmas resembling the glumes and exserted from them, awnless or rarely awned from the tip, 5-many-nerved, herbaceous to coriaceous; paleas 2-keeled, keelless or suppressed; lodicules usually 3; stamens usually 3 or 6 (rarely numerous), the filaments free or connate; stigmas 1-3. Fruit a caryopsis, sometimes with fleshy pericarp, rarely viviparous; starch grains simple, angular. Chromosomes small, basic number commonly 12.
± 45 genera in forests and woodlands in tropical and warm temperate regions; 2 species of Bambusa are cultivated in Pakistan, otherwise the tribe is locally represented by 2 genera each with a single species.
The tribe is usually easily recognised by its woody habit; the distinctive arm-cells and fusoid cells are a characteristic feature of leaf anatomy.
The bamboos retain, in those genera with 3 lodicules, 6 stamens and 3 stigmas, a floral structure reminiscent of the petaloid monocotyledons, and for this reason the tribe is often regarded as the most primitive in the grass family. Against this must be set the complexity of their vegetative organisation (for details of which see McClure, The Bamboos, 1966).
Some bamboos flower every year, but many flower gregariously in cycles of up to 60 years (120 years in Phyllostachys bambusoides, see Soderstrom & Calderon in Pacific Horticulture 37(3): 7-14. 1976). Gregarious flowering is often associated with sporadic flowering of isolated culms in the intervening years, and is usually followed by the death of the plant. The phenomenon is poorly documented and imperfectly understood (for summary see McClure, l.c.). The consequent paucity of good flowering material has distorted the taxonomy of the tribe, which must often be based on vegetative characters whose correlation with floral criteria remains uncertain
Bamboos are commonly grown for their constructional or ornamental value.