Endangered Species Day: Conophytum herreanthus

Conophytum herreanthus ssp. herreanthus, Hardy #637, Umdaus, Northern Cape, RSA (Oct. 9, 1961). Greenhouse cultivation in Connecticut, May 2017.

In honor of Endangered Species Day, here is a South African succulent that is definitely endangered, and in fact very likely completely gone from the wild. Conophytum herreanthus subspecies herreanthus was known from a single population from an area called Umdaus, northwest of the town Steinkopf in Northern Cape Province. Subspecies herreanthus was apparently always confined to a single gneiss and quartzite hill, and although it was originally abundant, its numbers declined in the mid-twentieth century, probably because of overgrazing, and overcollection for the succulent plant trade. I visited the site with a group of botanists in 1997, and we could only find one, nibbled-looking plant. The plant has apparently not been seen since then, and Steve Hammer and Andy Young, in the latest South African National Biodiversity Institute Red List of endangered plants, list C. herreanthus ssp. herreanthus as extinct in the wild.

Subspecies herreanthus is actually not uncommon in cultivation, at least among Conophytum specialists, with a number of different collections and probably many different individuals in circulation. An effort was made in the 1980s to introduce fresh seed and a small number of plants back into the wild at Umdaus, but nothing established over the long term.

Conophytum herreanthus ssp. rex at Klipbok, south of Eksteenfontein, Northern Cape RSA. August 2004.

Conophytum herreanthus occupies a unique evolutionary position in the genus, with a number of probable ancestral characteristics like leaf pairs that are only fused at their bases and a highly xeromorphic (drought-adapted) epidermis with stomata sunken beneath the surface and protected by special hairs. Fortunately for conservation purposes, there is a second subspecies, C. herreanthus ssp. rex, which is merely "rare" in the wild, according to the Red List. Subspecies rex is a larger plant with longer leaves, that is reasonably abundant in the area of the Little Helskloof and the town of Eksteenfontein, occupying a far larger range than subspecies herreanthus, with multiple populations. There are recent reports of a third area where C. herreanthus is found, to the west of Eksteenfontein, occupied by very large plants with a bluish coloration and prominent dots on the leaves; these plants could probably be accommodated in C. herreanthus ssp. rex, but could conceivably warrant description as a new taxon.

Matt Opel with Pachypodium namaquanum: habitat of C. herreanthus ssp. rex at Klipbok.

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Hammer, S.A. & Young, A.J. 2015. Conophytum herreanthus S.A.Hammer subsp. herreanthus. National Assessment: Red List of South African Plants version 2017.1. Accessed on 2017/05/20