Thursday, 10 January 2019

Zamia paucifoliolata: A new species of Cycad from the Pacific coastal forests of Valle del Cauca, Colombia.

Cycad’s are of particular interest to botanists and horticulturalists due to their unique evolutionary heritage; they are Gymnosperms (non-flowering Seed Plants), members of the group that includes Conifers and Ginkos, but among the closest non-flowering relatives of the Angiosperms (Flowering Plants). They large attractive plants, superficially resembling Palms, but producing large and often brightly coloured strobili, structures intermediate between cones and flowers; these are often pollinated by Beetles or Thrips. Cycads are thought to have originated during the Permian, and became dominant Plants in many ecosystems during the Jurassic and Cretaceous, but suffered heavily during the End Cretaceous Extinction, and there are about 330 species surviving today, predominantly in the Southern Hemisphere, most of which diversity is thought to have arisen from a post-Cretaceous radiation. Members of the genus Zamia are found from the southern United Stated though Central America and the Caribbean as far south as Bolivia. Zamias are deciduous shrubs, often growing from a subteranean rhizome (horizontal stem).

In a paper published in the journal Phytotaxa on 28 December 2018, Michael Calonje of the Montgomery Botanical Center, and Cristina López-Gallego and Jonatan Castro of the Universidad de Antioquia, describe a new species of Zamia from the Pacific coastal forests of Valle del Cauca, Colombia.

The new species is named Zamia paucifoliolata, in reference to the small number of leaflets on its leaves (no more than 18 on leaves up to 285 cm in length). The plant grows from an underground rhizome (buried horizontal stem) which produces erect leaves, singularly or in pairs, at regular intervals. Zamia paucifoliolata was found growing in a coastal forest with an average annual rainfall of 7000-7700 mm, making it one of the wettest terrestrial environments on the Earth. The species was found growing at only two localities, roughly 5 km apart, with a total known range of less than 3 km², for which reason Calonje et al. consider it to be Endangered under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species.

Zamia paucifoliolata in its natural habitat at the type locality. (A) Middle leaflets collected from plants at different stages of development. (B) Juvenile plant. (C) Adult plant with seed strobilus, showing yellow clay soils in which the species grows. (D) Adult plant in habitat with Jonatan Castro (left) and Michael Calonje (right). (E) The largest leaf yet observed for this species, measuring 285 cm long and carrying 18 leaflets. Calonje et al. (2018).

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