Dicentra uniflora Kellogg (Papaveraceae), a small, single-flowered, ephemeral geophyte, was studied at three main and several secondary forest sites at the southern end of the Cascade Range in California (2009–2018). Emergence was closely linked to snowmelt, with flowering to senescence taking six to seven weeks, at elevations ranging from 1350–2575 m. Plants transitioned from flowering to fruit maturation within three weeks. Percent seed set in this perennial was high, ranging from 81–93% over five sites; seeds per fruit ranged from 44–83. In 2018, weekly field observations quantified the fate of flowers on plants staked when flowers appeared: only 27–43% of the flowers produced mature fruits with seeds, 23–24% dried up, and 25–30% disappeared, often leaving the pedicels. Black-tailed deer are suspected to be the primary herbivore, although nocturnal larvae of the butterfly Parnassius clodius, known to consume Dicentra leaves, may also be responsible at higher elevations. Each seed bears an easily-dislodged elaiosome, but little of the expected seed dispersal by ants was seen throughout the study. Field plantings of seeds illustrated that germination can occur in winter, below the snow, with seedlings bearing only a single cotyledon emerging from the ground in the spring. A seedling quickly produces a tiny food-storing, belowground bulblet before disappearing with the summer drought of the Mediterranean-type climate. The second-year plant produces a new bulblet and sometimes a tiny tuber, but only a single leaf, and plantings in the field suggest that it may take up to 10 years or more before an individual reaches flowering stage. A flowering plant has one or two fusiform tubers approximately 21 mm long and a cluster of ∼9 whitish bulblets approximately 4 mm long. Published research in the closely-related D. cucullaria (L.) Bernh. indicates that bulblets are undeveloped food-storage leaf bases unique to four species of Dicentra, capable of giving rise to small plants and providing food for plant development. Bulblets planted in this field study clearly indicate they are capable of asexual reproduction. As in some other geophytes, dry weight of D. uniflora tubers was significantly greater in June at the beginning of the summer drought than in November when the plants began renewed root growth early in the fall wet season. The depth to the tops of tubers on plants occurring in clusters varied from 3.2–10.7 cm in the rocky, loamy or sandy-loamy soils of these sites.