An Afternoon at Yale

Marsh Botanical Garden cactus bed.

 

 

 

 Last weekend, the Connecticut Cactus and Succulent Society met at Yale University's Marsh Botanical Garden. The greenhouse complex at Yale includes a large modern structure with houses for botanical research, teaching and public displays, plus a couple of small legacy greenhouses that are mainly used for overflow space. One of the newer glass houses includes an open area with chairs and tables--used during the week for classes--where the CCSS held their meeting.

A pair of mature or nearly mature Welwitschia mirabilis plants at Marsh Botanical Garden.

 The cactus club was lucky enough to have a presentation by Dr. Michael J. Donoghue of Yale's Department of Ecology and Evolutionary Biology. Michael Donoghue is one of the best known plant evolutionary biologists active today. His talk for the CCSS covered Welwitschia, the peculiar xerophytic gymnosperm (cone-bearing seed plant) from arid northern Namibia and southern Angola. The fascinating lecture ranged from the history of Welwitschia's introduction to botanical science, with independent discoveries in 1861 by the Austrian medical doctor Friedrich Welwitsch as well as the artist Thomas Baines, to the latest findings from molecular phylogenetics, and finds of fossil Welwitschia-like pollen and cones.

Yearling Welwitschia seedling from the UConn teaching collections.

One point of interest from the talk, appropriate for the Darwin Day (February 12) season, concerned the evolutionary relationships of Welwitschia. The plant has long been known to be part of a small group of gymnosperms called the Gnetophyta, which also includes the genera Gnetum (broad-leaved tropical trees and lianas) and Ephedra (joint-stemmed shrubs of temperate deserts, the source of the stimulant ephedrine). The Gnetophytes as a whole were of somewhat uncertain affinities; an earlier idea was that they were the closest living relatives of the Angiosperms (flowering plants), based on details of their wood anatomy and pollination/fertilization process, as well as reproductive structures that resemble modified bisexual flowers. More recent evidence, primarily from DNA sequencing but also from the reinterpretation of anatomy and reproductive biology, indicates that Welwitschia and its allies are actually more closely related to the conifers (pines, cedars and their relatives).

Michael Donoghue at the February CCSS meeting.