Figure 3. Annual bursage 



( Ambrosia acanthicarpa ) illustration 













DESCRIPTION 



^^ 



GENERAL NONTECHNICAL DESCRIPTION: Annual bursage is a 

 branching annual, 2-15 dm (8-40 in) tall. It is 

 distinguished by several series of elongate, pointed spines 

 on the pistillate heads, and the mature heads are 6-10 mm 

 (1.8-5.2 in) long. Pistillate heads are in axillary 

 clusters below the elongate staminate inf loresence . Leaves 

 are opposite below, alternate above, petiolate or the 

 uppermost becoming sessile, and with a variable blade 

 outline from lanceolate to broadly ovate and 2-8 cm (0.8-2.4 

 in) long. The margins are lobed to 1-2X pinnatifid; the 

 lobes sometimes deeply dentate. The upper and lower leaf 

 surfaces are often both green, but the upper is sometimes 

 sparsely white-pubescent (adapted from: Great Plains Flora 

 Association 1986) . 



TECHNICAL DESCRIPTION: Branching annual, 2-15 dm (8-40 in) 

 tall, variously long-pubescent to hispid, or both. Leaves 

 opposite below, alternate above, petiolate or the uppermost 

 becoming sessile; blade variable but broadly ovate to 

 lanceolate in outline, 2-8 cm (0.8-2.4 in) long lobed to 1-2 

 X pinnatifid, the lobes sometimes deeply dentate, upper and 

 lower surfaces both green or the uppeer srface sometimes 

 sparsely white-pubescent. Staminate inflorescence 

 racemiform and often much branched, heads stalked, involucre 

 3-12 mm (1.2-4.8 in) across and 3-9-lobed; pistillate heads 

 in clusters below the staminate inflorescence, involucre 5- 

 10 mm (.31-. 62 in) long and up to 14 mm (.9 in) across, 1- 

 flowered, with several series of flattened, pointed spines 

 or spines occasionally reduced or absent. 



