Myosurus minimus (Least Mousetail) - photos and description




Looking straight down on plant in above photo.

Plants with 5 sepals and 0 to 5 petals.

Leaf in above photo. 

General: Tiny annual with a tuft of narrow, linear leaves. Plants glabrous, acaulescent.

Flowers: Flowers grow in terminal, solitary spikes, we measured spikes to 22 mm long. Flowers with 5 elliptical, greenish-white sepals, 0 to 5 linear, yellowish-green petals, and up to 10 stamens. We measured sepals at 3 mm long by 1 mm wide, and petals at 2 mm long by 0.5 mm wide.

Leaves: Leaves are all basal, we measured a leaf at 20 mm long by 1 mm wide.

Height: Height not given in Budd's Flora or Flora of Alberta. We measured plants to 35 mm tall.

Habitat: Prairie mud flats and moist depressions.

Abundance: Very rare, ranked as an S3 (as of 2021) by the Saskatchewan Conservation Data Centre.

Origin: Native.

Similar species: We have two Myosurus species native to Saskatchewan, I believe this plant is Myosurus minimus (and not the other species M. apetalus). Most of the taxonomic keys I have read to distinguish between these two species require observing the beak of the achenes. Achenes were not present, these plants were still flowering.

The Flora of Canada however, has a key for Myosurus that separates the two species on several other characteristics that I was able to observe with the plants I photographed:

- M. minimus with sepals to 3(4) mm long, M. apetalus with sepals to 2.5 mm long.
- M. minimus with stamens 5 to 10, M. apetalus with stamens usually 5.
- M. minimus with spike to  5 cm long, M. apetalus with spike usually not over 1 cm long.
- M. minimus with sepals lightly 3(5)-nerved, M. apetalus with sepals 1-nerved (rarely with a pair of faint lateral
  nerves). I did not observe any nerves on the sepals on the plants I found.

When and where photographed: Photos taken May 30th, during a steady rainfall, on a moist depression in prairie, Cypress Hills, about 450 km south west of our home in Regina, SK.