Vernal Pool Mousetail

Myosurus sessilis often grows with M . minimus , and hybrids between the two species are common. Because the plants mostly set seed by self-pollination, these hybrids often give rise to inbred lines showing the characteristics of the two parents in various combinations (D. E. Stone 1959). The names M . alopecuroides Greene and M . sessilis subsp. alopecuroides (Greene) D. E. Stone are based on the hybrid M . minimus × sessilis or on inbred lines descended from this hybrid.

Herbs , 0.8-2.5 cm. Leaf blades linear or nearly so, 1.6-7.4 cm. Inflorescences: scapes 0-0.2 cm. Flowers: sepals indistinctly 3-veined, scarious margins broad; petal claw about as long as blade. Heads of achenes 8-25 × 2-4 mm, immersed among leaves. Achenes: outer face narrowly rhombic or occasionally narrowly oblong, 1.2-2 × 0.4-0.8 mm, 2-4.5 times as high as wide, not bordered; beak 0.8-1.8 mm, 0.6-1.1 times as long as body of achene, diverging from outer face of achene, heads of achenes thus strongly roughened by projecting achene beaks. 2 n =16.

Calif., Oreg.

Flowering spring (Mar-May).

Vernal pools and alkalai flats; of conservation concern; 10-1600m.

Myosurus minimus Linnaeus var. sessiliflorus (Huth) G. R. Campbell

Myosurus sessilis is a species of flowering plant in the buttercup family known by the common name vernal pool mousetail. It is native to southern Oregon and the Central Valley of California, where it grows in vernal pools and other wet grassland habitat. It is an annual plant forming a small tuft up to about 10 centimeters tall. The leaves are narrow and linear in shape, measuring up to 7 centimeters in length. The inflorescence produces a single flower which has an elongated, cylindrical or cone-shaped receptacle up to 3 centimeters long. At the base of the receptacle are curving, spurred sepals and three to five tiny petals.