Photo of a shrub with small, needle-like leaves and large clusters of small white flowers. Scott Zona CC BY-NC 2.0.

The genus Adenostoma has just 2 spp., but both are endemic to western N America. This is Adenostoma fasciculatum, a common component of the chaparral vegetation in California. It is in subfamily #Amygdaloideae of the #Rosaceae. #California #Botany #PlantScience 🌾🧪

Photo of a large shrub with pinnately compound leaves & leaflets with crenate margins. There are large, flat-topped clusters of small white flowers. Scott Zona CC BY-NC 2.0.

Lyonothamnus is yet another monotypic genus from western N America. Lyonothamnus floribundus (#Rosaceae #Amygdaloideae) is endemic to the Channel Islands of California. It is not #cyanogenic, which is perhaps the evolutionary consequence of fewer predators on the islands. #CFP #Botany 🌾🧪

Close-up photo of a leafy shoot bearing small, white, 5-petaled flowers. Scott Zona CC BY-NC 2.0.

Oemleria is another endemic, monotypic genus of #Rosaceae #Amygdaloideae from western North America. Oemleria cerasiformis is dioecious, & its flowers are said to be foul-smelling & fly pollinated. Not exactly "a rose by any other name...." #Botany #PlantScience 🌾🧪

Photo of leafy shoots with clusters of small, red, fleshy fruits. Scott Zona CC BY-NC 2.0.

Heteromeles is another monotypic genus of #Rosaceae #Amygdaloideae (but it’s sometimes placed in the larger, Asian genus Photinia). Immature fruits of H. arbutifolia are cyanogenic. As fruits mature, the toxin shifts out of the mesocarp & into the seeds. #cyanogenesis #Botany #PlantScience 🌾🧪

Photo of leafy shoots with small leaves and large, yellow flowers. Photo by Laura Gaudette CC BY 4.

Coleogyne ramosissima is the only species in this genus of #Rosaceae #Amygdaloideae, & it’s an odd one: Opposite leaves, yellow sepals, no petals, 1 carpel, lateral style. It is wind-pollinated. Individuals have long lifespans. 📷: Laura Gaudette CCBY4. #Botany #PlantScience 🌾🧪