Synonyms of Toxicodendron diversilobum

Toxicodendron diversilobum. Rhus diversilola, Torr. & Gray, FL i 218.

E.L. Greene had the facility to view specimens, and immediately pronounce them as known or new species.  In 1905, Greene described several segregates from common poison oak, Toxicodendron diversilobum (T&G) Greene. 

These names do not appear in the Jepson eFlora, nor on the Interchange. They are below.

Greene remarked (in his Leaflets 1905 emphasis added):

This represents a peculiar type of Toxicodendron belonging exclusively to the Pacific coast. The leaflets and their lobes are in general rounded and obtuse rather than angular and acute; the panicles in the original as well as in most of the specific segregates, lax and pendulous, each fruit suspended on a rather long and slender pedicel.   But several inland species have their panicles as rigidly erect as in the Atlantic type of the genus. Typical T. diversilobum is from the lower Columbia, and is figured well in Hooker's Flora. The species seems to extend along the seaboard southward throughout western Oregon and California to about Monterey, exhibiting much diversity as to the lobing of the leaf, though the general outline of it remains the same. But south of Monterey other well defined species appear, and still more of them away inland among the mountains bordering arid regions in California, Oregon and Washington. Some of these, of which fair specimens occur in the herbaria, are here named and defined.

Toxicodendron comarophyllum Greene, Leafl. Bot. Observ. Crit 1(9): 120. 1905.

From Tighe's, near San Diego, Calif., Dr. Edw. Palmer, 1875.

BM000884727 & US00095833. The name has not been lectotypified

Toxicodendron dryophilum Greene, Leafl. Bot. Observ. Crit. 1(9): 121–122

Little Chico Creek, Butte Co., Calif. ... 1896 Mrs. R. M. Austin s.n. [in 1896]

“holotype” US00095837, isotypes NDG12268 and MO-2246530. The name has not been lectotypified

Toxicodendron isophyllum Greene, Leafl. Bot. Observ. Crit 1(9): 121. 1905.

River banks near San Jacinto in southern California, 9 March, 1898, J. B. Leiberg 3117

US00095841 is the only on line specimen

Toxicodendron oxycarpum Greene, Leafl. Bot. Observ. Crit 1(9): 121. 1905

Vicinity of Santa Cruz, Calif., July, 1884 J. Ball s.n. “ex region collina, California occidentalis,. Dedecante July. US00095850 is the only on line specimen.

Toxicodendron vaccarum Greene Leafl. Bot. Observ. Crit 1(9): 121. 1905

Cow Creek Mountains, Shasta Co., Calif. Baker & Nutting s.n. [in 1896]

NDG09527 & NDG09528.  The name has not been lectotypified.

The actual types, or choices for lectotypes is uncertain.  Greene then became an associate in botany at the Smithsonian Institution in 1904, hence the most likely home to potential lectotypes is US.  Greene moved to South Bend, Indiana along with his library and herbarium specimens, which are now at NDG. 

Uncertain typification of these names means little if one has poison oak dermatitis.