I have grown Alyssoides utriculata for a number of years and I never see it mentioned in discussions. It really does deserve more attention. It is bright yellow, very easy to grow, seems long lived and makes really unusual seed heads. Consider this one for your rock garden.
My plants were grown from seed that I got from the Ontario Rock Garden and Hardy Plant Society Seed Exchange. At the time it was named Lesquerella kingii and several in the society grow it under this name. I must confess that I even submitted seeds under this name and then last year I looked it up to check the name and found that it was really Alyssoides utriculata. It doesn’t look anything like Lesquerella kingii.
Common names for the plant include bladderpod, Greek bladderpod and inflated bladder seed, which are clearly based on the odd seed pods which are quite large and distinct. The common name bladderpod is also used for the California native Peritoma arborea, which has even larger seed pods. The dried seed stocks are used for flower arrangements.
All of the information I was able to find on this plant says it is a perennial, but in my opinion it’s a subshrub. It does not die back completely in winter and it makes quite woody stems. New spring growth originates from the upper part of these stems. Over time the plant gets taller and has leggy lower stems, not unlike lavender which is also a subshrub. If you cut the plant to the ground it will likely be killed. Once it is too leggy, about every 4 years, just take some stem cuttings in spring which root very easily. Or grow more from seed.
The plant makes a clump about a foot in diameter making it more suitable for a rock garden holding larger plants or a regular boarder garden.
Life Cycle: sub-shrub
Height: 20cm (10in)
Bloom Time: late spring
Natural Range: Balkans
Habitat: alpine rocky slopes
Synonyms: Alyssoides graeca, Vesicaria graeca, Alyssum utriculatum, Alyssum graecum
Cultivation of Alyssoides utriculata :
Soil: sandy, lean
USDA Hardiness Zone: 6– 9
Propagation: seed, softwood cuttings