Descurainia pinnata (Walter) Britton
western tansy mustard
Brassicaceae (Mustard family)

Introduction to Vascular Plants

Photograph

© Virginia Skilton     (Photo ID #25534)


Map

E-Flora BC Static Map

Distribution of Descurainia pinnata
Click here to view the full interactive map and legend

SUBTAXA PRESENT IN BC

Descurainia pinnata ssp. brachycarpa

Species Information

General:
Annual herb from a taproot; stems 10-60 cm tall, simple or branched above, sparsely hairy, multibranched, often stalked-glandular above.
Leaves:
Basal and lower stem leaves once or twice pinnately lobed, linear to egg-shaped, hairy, 3-10 cm long; upper stem leaves once pinnate to almost entire, generally glabrous, rarely glandular, 1-10 cm long.
Flowers:
Racemes elongate; flower stalks 6-12 mm long, at about 45 degrees to axis of inflorescence; petals yellow, erect, 2-3 mm long, exceeding sepals by about 0.5 mm; sepals 1.5-2.5 mm long.
Fruits:
Siliques, somewhat thicker towards the tips, rounded above, about as long as or shorter than the stalks, 7-12 (15) mm long; styles short, not beaklike; seeds 1-20 per chamber, partially in 2 rows, about 0.8 mm long.
Notes:
Two highly variable, and often intergrading, varieties occur in our region.

1. Siliques 4-12 mm long, usually nearly equal to or longer than the stalks....................... ssp. intermedia (Rydb.) Detl.

1. Siliques 10-20 mm long, usually shorter than the stalks.................. ssp. filipes (A. Gray) Detl.

SourceThe Illustrated Flora of British Columbia

Ecology

Ecological Framework for Descurainia pinnata

The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)

Site Information
Value / Class

Avg

Min

Max

Elevation (metres)
721 283 1685
Slope Gradient (%)
40 0 90

Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]

188 25 360
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
2 0 5
Modal Nutrient Regime
Class
C
# of field plots
 species was recorded in:
91
Modal BEC Zone Class
BG

All BEC Zones (# of stations/zone) species was recorded in

BG(41), BWBS(2), ESSF(1), IDF(19), MS(1), PP(15), SBS(5)

Habitat and Range

Dry shrublands and waste places in the montane and steppe zones; common in S BC, S to E WA, CO, NV and E CA.

SourceThe Illustrated Flora of British Columbia