About Asclepias rubra L.
Note: Gray (in Proc. Amer. Acad. Arts 12: 90. 1876) used the expression 'founded upon' (not acceptable as equivalent to 'type') in relation to Clayton 263 (BM). Woodson (in Ann. Missouri Bot. Gard. 41: 80. 1954) designated 310.39 (LINN) as the type. However, the sheet lacks the Species Plantarum number (i.e., '17') and was added to the herbarium after 1753, so it is not original material for the name.