Amphiachyris dracunculoides (DC.) Nutt.

Broom Snakeroot


CC = 3
CW = 5
MOC = 27

© DETenaglia

Family - Asteraceae/Astereae

Habit - Taprooted annual, sometimes with slightly woody base.

Stems - To 60 cm tall, erect, branched, herbaceous, typically single from the base and simple in the basal 1/2-2/3. Lower stem appearing woody, 3-5 mm in diameter, grayish-brown. Stems in inflorescence divaricate, glabrous, green, angled or grooved.

Amphiachyris_dracunculoides_lower_stem.jpg Lower stem.

© DETenaglia

Amphiachyris_dracunculoides_upper_stem.jpg Upper stem.

© DETenaglia

Leaves - Mostly absent at anthesis. Leaves of the inflorescence linear, sessile, with punctate dots (use lens to see) and minute serrulate teeth on the leaf margins (use lens to see), +/-1 mm broad, to 6cm long.

Inflorescence - Many small flower heads terminating each branch of the inflorescence. Stems spreading to +/-50cm broad at anthesis in a "mound" shape. Each flower head subtended by linear bracts giving way to the involucre.


© DETenaglia

Involucre - 2-3 mm broad, 2-3 mm tall, essentially biseriate. Lower series with green phyllaries. Phyllaries glabrous, linear-lanceolate, 2 mm long, 1 mm broad, acute. Inner series of phyllaries yellow-green (translucent at the base), glabrous, 3 mm long, 1.5-1.8 mm broad at the apex, acute, with the apical 1/4 spreading outward.


© DETenaglia

Ray flowers - +/-8 per flower head, spreading, pistillate and fertile. Ligule yellow, 3-4 mm long, 2 mm broad, elliptic-oblong, glabrous, with 2 impressed veins above (expressed below). Corolla tube 1-1.5 mm long, whitish, glabrous. Style slightly exserted and bifurcate, whitish, .5-.6 mm long, glabrous. Stigmas 1 mm long, yellow, glabrous. Pappus absent or a minute, translucent crown.

Disk flowers - Disk +/-3 mm broad, with +/-15 flowers. Flowers staminate. Corolla tube translucent-yellow, glabrous, 3 mm long, 5-lobed. Lobes spreading, yellow, acute, +/-.5 mm long, glabrous. Stamens 5, adnate at the base of the corolla tube. Filaments translucent, .7 mm long. Anthers yellow, connivent around the undivided style, 1 mm long, partially exserted. Style +2 mm long, translucent in the basal 2/3, with the apical 1/3 pubescent and yellowish and exserted. Receptacle flat, naked but with ridges around the flower bases. Pappus a translucent awned crown. Awns equaling or exceeding the corolla. Crown (undivided portion) short, .3-.5 mm long.


© DETenaglia

Fruits - Achenes 1.5-2.2 mm long, oblong-obovoid, sometimes slightly flattened, with 7-9 fine, green nerves, the surface otherwise densely pubescent with short, white hairs, purplish brown to nearly black.

Flowering - July - October.

Habitat - Upland prairies, limestone and dolomite glades, bluff tops, riverbanks, fallow fields, disturbed sites, roadsides, railroads.

Origin - Native to U.S.

Other info. - This attractive little species can be found in the southwest corner of Missouri. Although it is not seen in the plant photo above, the plant nearly always grows from a single trunk-like base and then branches widely in the upper half (the whole plant being as wide or wider than tall). This species grows in profusion along roadsides in parts of the Great Plains and is quite common there. It is far less abundant in Missouri.

A synonym is Gutierrezia dracunculoides (DC.) S.F. Blake

Photographs taken at Tall Grass Prairie National Preserve, KS., 9-18-06.