52 Rhodora [Marcu 
common around Philadelphia, where “in dry and exposed situations 
...-It.... becomes very hairy, in wet places often perfectly smooth.” 
Although, as with the early writers generally, there may have been 
confusion in Nuttall’s mind with others of the closely related species 
of this group, his description applies with sufficient distinctness to the 
O. fruticosa (typical) of our manuals to justify the adoption of his 
name for that form in its present varietal rank, as O. nyBRIDA Michx. 
var. ambigua (Nutt.). I refrain from citing other probable synonyms 
of this form because of the uncertainty which, in the absence of 
authentic specimens, must attend the identification of the older 
descriptions of members of the Kneiffia group. 
7. Thapsia trifoliata L. Sp. i. 262 (1753).! The Gronovian refer- 
ence is based on Clayton 291, which is a young specimen of the plant 
called in the 7th edition of Gray’s Manual Thaspium aureum Nutt. 
var. atropurpureum (Desr.) Coult. & Rose. The synonymy of the 
yellow form of this species and of Zizia aurea (L.) Koch has become 
badly confused. Thus Thaspium aureum Nutt., used by Coulter & 
Rose (Bot. Gaz. xii. 135 (1887)) and by the 7th edition of Gray’s 
Manual, is based by Nuttall (Gen. i. 196 (1818)) on the name-bringing 
synonym Smyrnium aureum Pursh, Fl. i. 196 (1814), which in turn 
rests on the same name of Willdenow (Sp. i. 1468 (1798)), and this on 
that of Linnaeus (Sp. ed. 1. i. 262 (1753), ed. 2. i. 377 (1762)). The 
same Smyrnium aureum of Linnaeus is also the basis of Zizia aurea 
Koch, Nov. Act. Caes. Leop. xii. 129 (1825). Obviously the name 
Smyrnium aureum can not continue to do service as the basis of specific 
names in two different genera. Linnaeus’s S. aureum is now recog- 
nized as applying to the Zizia (Z. aurea (L.) Koch), and the name to be 
used for the purple-flowered Thaspium is accordingly THASPIUM 
TRIFOLIATUM (L.) Gray (as to syn.), Man. ed. 2. 156 (1856), with which 
Smyrnium atro-purpureum Desr. in Lam. Ency. iii. 667 (1789), with 
its various subsequent combinations, is synonymous. For the yellow- 
flowered form it becomes necessary to create a new name, since the 
various designations hitherto in use have been based on Thaspium 
aureum Nutt., which as has been shown rests on Smyrnium aureum L. 
and is not applicable to the Thaspium. It may be called: 
1 Thapsia trifoliata, 
“4, THAPSIA foliis ternatis ovatis. 
“Sium folio infimo cordato, caulinis ternatis; omnibus crenatis. Gron. virg. 31. 
“* Habitat in Virginia. 
“Semina singula gaudent alis 5, longitudinalibus, membranaceis, & involucra nulla sunt uti 
in praecedente, cum qua genera conjungo, quamvis facie diversa.” 
