Culms 15–60 cm. Some or all spikelets bulbiferous, their florets modified into leafy bracts; sometimes the basal florets within a spikelet more or less normal and only the distal florets bulbiferous. Calluses usually sparsely webbed, sometimes glabrous; lemmas glabrous or softly puberulent over the keel and lateral veins, sometimes between the veins; anthers in the least deformed florets 1.2–1.5 mm or aborted late in development, absent from modified florets. 2n = 21, 28, 31, 32, 33, 34, 35, 37, 39, 42+I, 44, 46, 48, 49.
Poa bulbosa subsp. vivipara was introduced from Europe into the Pacific Northwest as a forage grass; it has since spread across temperate areas of the Flora region, particularly in the Pacific Northwest and northern Great Basin. It is highly tolerant of grazing and disturbance. Plants within an individual population may vary considerably in their proportion of viviparous florets; there may even be a few plants that produce no viviparous florets.