Shinnersoseris rostrata (Annual Skeletonweed) - photos and description


Lower stem leaf in above photo

I count 9 petals in the above photograph

General: Annual plant with a much branched growth habit, and with long, linear leaves. Plant glabrous.

Flowers: Flowers are terminal, small, pinkish white, with 6 - 10 ray florets, we counted 9 ray florets in the photo shown above. Flower in above photo was 7 mm in diameter.

Leaves: Lowest leaves opposite and upper leaves alternate, the leaves have sharp tips. I measured a leaf to be 8.5 cm long and 3 mm wide.

Height: Height is listed in Budd's Flora to 60 cm, the plant in the above photo was 17 cm tall.

Habitat: Active and stabilized sand dunes.

Abundance: Very rare, ranked as an S2 (as of 2021) by the Saskatchewan Conservation Data Centre.

Origin: Native.

Synonym: Listed in some of the guides we use as Lygodesmia rostrata.

Similar species: It's easy to confuse this plant with perennial Skeletonweed, Lygodesmia juncea. The plants can be readily distinguished if you find them in flower, the flowers of the Lygodesmia juncea are considerably larger 2 cm in diameter, have only 4 or 5 petals, with the petals toothed. Also, the leaves of Lygodesmia juncea are seldom over 5 cm long, while the leaves of Shinnersoseris rostrata grow from 5 to 20 cm long. And, the leaves near the top of the stems of Lygodesmia juncea are very short almost scale-like, while those of Shinnersoseris rostrata are long.

When and where photographed: Photos taken July 8th, sand dunes, Douglas Provincial park, about 200 km northwest of our home in Regina, SK