Flytrap Dogbane, Spreading Dogbane: Apocynum androsaemifolium - The following 2 taxa are no longer recognized as separate but are now lumped together as A. androsaemifolium. I've kept them separate here as it is possible to identify them separately.
Spreading Dogbane, Bitter Dogbane: Apocynum androsaemifolium var. androsaemifolium (Synonyms: Apocynum androsaemifolium ssp. androsaemifolium, Apocynum androsaemifolium var. incanum)
Dwarf Dogbane: Apocynum androsaemifolium var. pumilum (Synonyms: Apocynum androsaemifolium ssp. pumilum, Apocynum androsaemifolium var. tomenstellum, Apocynum pumilum, Apocynum pumilum var. pumilum, Apocynum pumilum var. rhomboideum)
Clasping-leaved Dogbane, Common Dogbane, Hemp Dogbane: Apocynum cannabinum (Synonyms: Apocynum cannabinum var. cannabinum, Apocynum cannabinum var. glaberrimum, Apocynum cannabinum var. pubescens, Apocynum cannabinum var. suksdorfii, Apocynum sibiricum, Apocynum sibiricum var. salignum, Apocynum suksdorfii)
Western Dogbane: Apocynum xfloribundum (Synonyms: Apocynum medium, Apocynum medium var. floribundum, Apocynum medium var. lividum, Apocynum medium var. medium, Apocynum medium var. vestitum)
Milkweeds: The Genus Asclepias
Sacromento Waxy Dogbane: Cycladenia humilis var. humilis - Introduced but not naturalized.
Greater Periwinkle, Large Periwinkle: Vinca major - Introduced.
Common Periwinkle, Lesser Periwinkle: Vinca minor - Introduced.