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| Welwitschia mirabilis, Henry Doorly Zoo, Omaha, NE 12/30/2011 |
This is Welwitschia mirabilis. It's a member of the phylum (or division, if you're a botanist) Gnetophyta, which otherwise includes 50 or so species of Ephedra and 35 species of Gnetum. It's a gymnosperm, like pines, cycads, and Ginkgo biloba. This means that it doesn't produce flowers. Despite that, it does produce nectar, and is insect pollinated, mostly by flies and some true bugs.
The fossil record of the gnetophytes indicates that they used to be more diverse, especially in the Cretaceous period. As the last remnants of a once notable group, and an odd-looking one to boot, Welwitschia is often labeled a living fossil. But in fact, its seemingly primitive appearance appears to be largely an adaptation to living in one of the drier places on Earth -- Welwitschia is only found wild in the Namib desert of SW Africa. In addition to being insect-pollinated (a trait it shares with Gnetum, but is otherwise unknown in the gymnosperms), it uses a photosynthetic pathway found in some dry country angiosperms, known as crassulacean acid metabolism (or CAM). (1) On the other hand, it doesn't use it much, although noone's really sure why. Another trait that Welwitschia and the other gnetophytes share with angiosperms is a particular form of vascular tissue, referred to as vessel elements.
Despite these similarities, molecular data indicates that the gnetophytes are actually most closely related to conifers, not angiosperms, which means that the CAM, the vessel elements, and the use of nectar to attract insect pollinators must all have evolved independently of the angiosperms. That's hardly what I expect out of a living fossil.
(1) von Willert, D. J., Armbrüster, N., Drees, T., & Zaborowski, M. (2005). Welwitschia mirabilis: CAM or not CAM—what is the answer?. Functional Plant Biology, 32(5), 389-395.
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