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Flora of Taiwan | Family List | Compositae | Ambrosia

Ambrosia psilostachya DC., Sp. Pl. 102. 1753; Nagada T., Ill. Jap. Alien Pl. 254. 1972; Britton, N. L. & H. A. Brown. An Ill. Fl. of the Northern United States and Canada 3: 266. f. 1970.


Erect annual or perenial herb. Stem up to 150 cm high with branched panicles in the upper half. Leaves hairy or rough on short stalks, each 5 to 12 cm long, ovate-lanceolate, deeply lobed often with toothed segments; lower leaves opposite, but upper leaves alternate. Male flowers several, not exceeding the involucre, grouped within shortly stalked hemispherical heads in terminal spike-lile racemes, with up to 6-8 connate bracts forming an involucre. Corolla 4-5 mm, lilac, infundibuliform with a long tube, with 4 lobes. Calyx with 6 teeth, persistent in fruit; stamens 4, inserted on the tube of the corolla. Filament slender; anthers small, oblong, and exerted; style filiform and bifid; branches unequal. Female florets few, without a corolla, in 1-flowered heads in the axils of upper leaves; ovary 2-locular with 1 ovule in each loculus. Achene 2-7 mm, scabrid, dry with 1 seed.

KAOHSIUNG: Panpingshan, Tseng 2350; Tseng 2557; Tseng 2676 (TESRI).

A. psilostachya is native to North America, and has been introduced to Japan, Germany , Spain and New South Wales of Australia from where it has spread to the eastern and southern Australia. In Taiwan it was found in Kaohsiung County.

Tseng, Y.-H. & C.-I. Peng. 2004. Ambrosia psilostachya DC. (Asteraceae), a newly naturalized plant in Taiwan. End. Sp. Res. 6(1): 71-74.


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