Common name : Chickenspike, gooseweed, wedgewort
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Diagnostic characters
Biology
Ecology and distribution
Nuisance
Weed control
Botany
Uses/Remark
References
Sphenoclea zeylanica is an erect or suberect, glabrous, semi-aquatic annual herb.
Plant, up to 150cm tall, somewhat succulent with more or less hollow stem. The inflorescences are cylindric, and the minute white or greenish-yellow flowers are densely crowded, though characteristically only 1 or 2 open at a time.
Propagation by seeds.
In and near pools, swamps, streamsides, periodically inundated depressions, ditches, irrigation channels, and wet places generally, 0-1250m.
Widespread in tropical Africa and also in Madagascar; widespread (but probably introduced) in tropical Asia and America.
Gooseweed is a 2_4-D resistant biotypes in rice fields in South-East Asia. This is a result of over 20 years, of repeated use of the same herbicides.
Habit
Stem hollow, up to 150cm tall, often much branched.
Roots
Roots numerous, long, cord-like.
Leaves
Leaf-blade oblong to lanceolate-oblong, attenuate at both ends, acute or obtuse, 2.5-12.5cm long; subsessile to petiolate; petiole up to 2.5cm long.
Inflorescence
Spikes cylindric, up to 7.5cm long, narrowed at apex; peduncle up to 8cm long. Flowers densely crowded, though characteristically only 1 or 2 open at a time, rhomboid or hexagonal by compression, sessile, wedge-shaped below, attached longitudinally to the rhachis by a linear base. Corolla whitish, pinkish or purplish, 2.5-4mm long;
Fruit
Capsule 4-5mm diameter, dehiscing below the calyx-segments which fall with the lid, leaving the scarious base persistent on the rhachis.
Seeds
Seeds numerous yellowish-brown, 0.5mm long.
- Shaw, H.K.A. 1968. Sphenocleaceae. In: Flora of Tropical East Africa, E. Milne-Redhead and R. M. Polhill, eds. pp. 1-2.
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