Primula is a genus in the Primulaceae family with more than 400 species mostly distributed in the Northern Hemisphere and mostly growing in woodlands and cold mountain conditions in the Himalayas and China. Most of them are herbaceous perennials, often grown as spring annuals in climates where they are unlikely to survive to the next year. Only a few would be considered geophytic.
In 2007 in a paper entitled Transfer of Dodecatheon to Primula (Primulaceae) by Austin Mast and James Reveal, Dodecatheon was moved to Primula on the basis of DNA testing. It became Primula section Dodecatheon (L.) A. R. Mast & Reveal as a member of Primula subgenera Auriculastrum. These species look very different from most Primula species are believed to have evolved from a primula ancestor through the actions of buzz pollination by bees. Since this change seems to be adopted we are now including geophytic species that were formerly on our Dodecatheon page here. The species in section Dodecatheon, widely known as "Shooting Stars" or "Mosquito Bills", look a bit like miniature Cyclamen, but with projecting anthers that give the flowers a pointed look. They are widespread in North America, extending from northwestern Mexico to northwestern Canada, Alaska and also part of northeastern Siberia. In California there are two basic categories: high-elevation species that bloom in the late spring or summer and occur in moist habitats, and lowland species that bloom in late winter or spring and grow in the winter-wet, summer-dry Mediterranean climate regions of the state. Species have basal clumps of leaves and nodding flowers produced at the top of tall stems. In this wiki we include species that go completely dormant for part of the year and can be grown like bulbs. Rhizomes or caudices are usually present with fibrous roots and sometimes bulblets. The caudex is generally short-lived in most species and may or may not be obvious when the plants are dormant. Species are buzz pollinated by large bees. For more information on this former genus see Revision of Dodecatheon by James L. Reveal.
Primula clevelandii (Greene) A. R. Mast & Reveal, syn. Dodecatheon clevelandii Greene, ranges from central and southern California to northern Baja California where it grows on grassy slopes and flats in chaparral, foothill woodland, and valley grassland communities. The plants grow in areas that are completely dry for five or six months in summer and fall, and they disappear underground during summer dormancy. In cultivation, they do well in pots, and can be grown in the same conditions used for summer-dormant bulbs. They will also reportedly tolerate some summer water if grown in very well-drained soil. When dormant, the roots of this species are brittle and spider-like. They must be handled very gently to avoid breaking the roots. There are several varieties of this species, Primula clevelandii var. gracilis (Greene) A.R.Mast & Reveal, Primula clevelandii var. insularis (H.J.Thomps.) A.R.Mast & Reveal, and Primula clevelandii var. patula (Kuntze) A.R.Mast & Reveal. They are distinguished by the colors of the anthers and pollen sacs. This plants photographed here are apparently var. patula. They are second-year seedlings growing in a paper coffee cup. Photos by Michael Mace.
A year after those photos were taken, the plants had been moved to a pot and were in bloom again:
Primula hendersonii (A.Gray) A.R.Mast & Reveal, syn. Dodecatheon hendersonii A.Gray, is a species of grassland communities and oak and conifer woodlands where it is found in sunny or often shady places. It occurs from British Columbia, Canada, south to California. Common names are Henderson's shooting stars and mosquito bills. Spoon shaped leaves are in a basal rosette and appear in winter. This species flowers in early spring and then dies back when the rains stop (late spring to summer). The flowers are inside out with magenta to lavender to white petals and a yellow or whitish tube with a thick, wavy, reddish to reddish-purple ring. They appear on top of a tall 12 in (30 cm) leafless flower stalk. The flowers are pendant when they first open, then turn upwards once pollinated. The seed capsules form small upright cups that hold the small (poppy seed size) seeds. When the wind blows or the dried stems break, the seeds spill out. This also makes seed collection easy, just pick the dried scape and spill the seeds into a container of some type for storage.
Richard Haard in a PBS list post reports that the offsets around the crown can be harvested to form new plants. Travis Owen reports that it is easy to transplant in the fall before the vegetative cycle begins. Any rhizomatous sections that accidentally break off can be planted and will form mature plants in a few years. Mary Sue has some planted in the ground and others grown in a pot moved to the shade in summer and not watered until it naturally starts to rain sometime in the fall.
Photos below were taken by Mary Sue Ittner showing the plant in various stages from bud to fruit. The last photo of the rhizome and roots on a 1 cm grid was taken September 2013 several months after the plant had gone into dormancy and kept dry.
Photos from Mary Sue Ittner were taken March 2016 where it was growing in Sonoma County, California on the bank on a shady forested road.
Photos below by Travis Owen of plants in habitat under Arbutus menziesii, Pseudotsuga, and Pinus trees, and among various grasses and herbs like Antennaria. First photo shows plants in bud, mid February 2015. Second photo shows the first flower opening in late February, 2015, note that the petals have not yet reflexed. Third shows mature plants under a pine tree. Last photo shows ripening seed pods, still colorful and beautiful. What is left of the stigma will pop off when the seeds are ready, creating a small urn that will spill the seeds when they are mature.