Townsendia exscapa (Low Townsendia) - photos and description
Petal about 16 mm long.
Involucre about 11.5 mm wide.
Bracts labeled "A' without a tuft of hairs on tip, labeled "B" with
ciliate margins.
General: Low-growing, acaulescent plants, with a tufted growth habit. Plant is described as perennial in all our field guides. I have grown this in our rock garden from wild collected seed for several years, the plants have always been biennial.
Flowers: Flower heads showy acaulescent (growing
among the basal leaves), bright white, we measured the petals from 14 mm
to 16 mm in length, the involucre at 12 mm wide, and a flower head at 30
mm diameter.
A couple of guides mention that T. exscapa does not have a
fringe of hairs on the tips of its bracts to distinguish it from T. hookeri which has a tuft of
hairs on the tips of its bracts. However the bracts of T. exscapa
are cilliate - the margins do have a fringe of hairs. I've found this a difficult judgement call of merely a ciliate
margin on the bract tip of T. exscapa versus a tuft of hairs on
its bract tip.
Leaves: Leaves all basal, are linear to narrowly spatulate, measured to 42 cm long including petiole, and 3 mm wide. Leaves have a close, fine pubescence, top and bottom, giving the foliage a greyish green colour.
Height: Not applicable.
Habitat: Prairie hilltops.
Abundance: Fairly common, ranked as an S4 by the Saskatchewan Conservation Data Centre. Uncommon to rare in our experience.
Origin: Native.
Similar species: Very similar to the less common Townsendia hookeri, however that plant is smaller having flower petals 8 to 12 mm long (Flora of North America), an involucre 8-18 mm wide (Flora of North America), and with a tuft of hairs at the tip of involucre bracts (Flora of the Great Plains). Whereas Townsendia exscapa is larger with flower petals (ray florets) from 12 to 18 mm long (Flora of North America), an involucre 12 to 25 mm wide (Flora of North America), and without a tuft of hairs at the tip of involucre bracts (Flora of the Great Plains).
When and where photographed: Photos taken May 12th and May 13th on the grassy slopes of the Qu'Appelle Valley, 35 km north of Regina, SK and May 4th and May 20th on sandy, prairie hillsides, Douglas Provincial Park, about 175 km northwest of our home in Regina, SK.