Wednesday, October 7, 2015

David Douglas in California, and the type of the Santa Cruz Tarplant (Holocarpha macradenia)

Type stations are vague: many type specimens of California endemic plants collected long ago cannot be attributed to a specific date or specific place.

The type specimen of the Santa Cruz tarplant was collected by David Douglas.  In, 1836 DeCandolle described it as Hemizonia macradenia in Prodromus (“Systematis Naturalis Regni Vegetabilis”), a 17-volume treatise on botany last updated by his son A. de Candolle in October 1873. 

The protologue statements are: “in Nova California legit cl. Douglas” and “v. s. comm. ab hon. Soc. hort. Lond.).  [recall here that typesetting was then manual and abbreviations were used prolifically, but not exactly diagnosed: none of these abbreviations derive specific problems here]. 

There are three specimens of the original Douglas collection, two at Key and one at the de Candolle herbarium in Geneva: barcodes K001079845, K001079846 and G00453655.  All three sheets are attributed to Douglas and to 1833.  Based on the narrative detailing Douglas travels in California (in “California Frontier Naturalists” Biedelman 2006 pages 116-125, the best approximation is that Douglas collected the fall of 1831 and somewhere within a day’s ride of Monterey.  The most probable station therefore being in far northern Monterey County.  One proviso is that H. macradenia is often in peak bloom in September and early October, and the two Kew specimens are clearly in nice flower.  If Douglas had ventured north to Santa Cruz in the fall of 1831, then no mention is given in Biedelman, hence the type station is not very probably directly attributed to Santa Cruz county.  Accordingly, this raises the possibility that H. macradenia might have been VERY extensive in northern Monterey County, and since has contracted significantly. Presently, there is but a singe Monterey County occurrence.  Threrefore, Douglas may have obtained the type somewhere in the vicinity of present day occurrences at Elkhorn Slough and vicinity. 

Based on the narrative in Biedelman (2006) Douglas specifically visited Santa Cruz in February, 1831, but H. macradenia would not have been in flower at that time.

Regardless, the type was not likely to have been collected in 1833, because on November 4th, 1833 Douglas only arrived at San Francisco via Ft. Vancouver, having been away from California.  Douglas had been at destinations other than those in the known geographic range of H. macradenia between March 1832 and August 1832, thence he departed San Francisco for the Sandwich Islands (Hawai’i) in November, then returned again, departing the final time at the end of November 1833.  Holocarpha macradenia has never been documented on the San Francisco peninsula. 

Accordingly, I attribute the holotype to: Monterey County, vicinity “Bolsa Neuva Moho Cojo” [36.80023/- 121.71204], David Douglas s.n. , ±September 1831.

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