Orchid optimists

Several species of orchids found at Verloren Valei flower before the summer rains fall, thus acting as true harbingers of spring—effectively risking the “capital” they built up during the previous season on the expectation that the rains will come.

Orthochilus vinosus - a pre-rainfall flowering orchid (Photograph by Gerrit van Ede)
Orthochilus vinosus – a pre-rainfall flowering orchid (Photograph by Gerrit van Ede)

Most of South Africa is a summer rainfall area, with little rain in the winter months. These areas therefore experience a distinct dry period before the summer rainfall starts in late spring. It is therefore possible to refer to plants that flower in the dry spring months before the onset of the summer rains as pre-rainfall flowering plants.

These plants store sufficient nutrition to enable flowering before growth starts. Many members of the large orchid family—Orchidaceae—fall into this group, many of which are represented at Verloren Valei. The most well-known of this group is Eulophia hians var. hians and Disa baurii. These plants flower late September till early November on the Reserve.

Another member of this group which has become synonymous with Verloren Valei is Orthochilus vinosus—although arriving at the correct classification was somewhat difficult, as it so often is with wild orchids.

When Frans Krige found the first specimens in flower on Verloren Valei, I did send examples to the Bolus Herbarium and the initial decision from Dr Anthony Hall was that it was a variety of Orthochilus leontoglossus. However, Frans and I were unhappy with this classification as there are significant differences between this orchid and Orthochilus leontoglossus. The former species flowers when the leaves are at most partially developed with peak flowering in October, flowers are scented and the uppermost bract on the scape not reaching the inflorescence(section of the flower spike carrying the flowers). The plants occur in scattered colonies on Verloren Valei.

By contrast, Orthochilus leontoglossus occurs occasionally and flowers in December – January on the Reserve and has then well developed leaves. Douglas McMurtry et al eventually described this species under the name Eulophia vinosa in the Field Guide to the Orchids of Northern South Africa and Swaziland.

Subsequent DNA research on the Eulophiinae sub-tribe meant that some plants that were originally considered to be part of the Eulophia genus were reassigned to the Orthochilus genus. Eulophia vinosa was one of them and became Orthochilus vinosus. Morphologically, the species in the Orthochilus genus have one characteristic in common: their petals and sepals are similar in form.

These beautiful flowers are a welcome sight in their own right, and as a sign that spring has come at last—and that the rains are expected.


References

Martos, Florent, Johnson, Steven D, Peter, Craig I & Bytebier, Benny, “A molecular phylogeny reveals paraphyly of the large genus Eulophia (Orchidaceae): A case for the reinstatement of Orthochilus”, Taxon 63(1), 20 February 2014, pp. 9-23(15), available at International Association for Plant Taxonomy.

McMurtry, D, Grobler, L, Grobler J & Burns, S, Field Guide to the Orchids of Northern South Africa and Swaziland (Pretoria: Umdaus Press, Pretoria, 2008).

Johnson, SD, Bytebier, B and Stärker, H, Orchids of South Africa: A Field Guide (Cape Town: Struik Nature, 2015).

Leave a Reply

Your email address will not be published.