Sytematics and evolution of the genus Heliamphora (Sarraceniaceae)

The genus Heliamphora belongs to the carnivorous plant family Sarraceniaceae (Ericales) and comprises 23 species, of which eleven have been described in the past seven years (Fleischmann et al., 2009). All of them are fibrous-rooted herbs with inflated, tubular pitcher-like leaves. The general habit is a lax rosette of leaves, although two species may develop monopodial stems up to 4 m tall (Berry et al., 2005; Maguire 1978).

The carnivorous pitcher leaves of Heliamphora are usually broadly tubular, widening from a ventricose lower part to a tubular or flaring upper part (pitcher mouth), usually with a notable constriction between those two parts. The pitchers may reach 5 – 50 cm in height, depending on species and growth conditions (plants growing in more shaded conditions usually develop taller and wider pitchers compared to individuals exposed to full sunlight). The pitcher appendage (lid) varies considerably between different species: generally, it’s more or less spoon or helmet-shaped and held over the elliptic pitcher mouth; but some species bear a ligulate-oblong, upright appendage, whereas in one species, H. folliculata, a unique lid that serves as nectar reservoir has evolved. In H. sarracenioides and H. exappendiculata, the lid is not developed or strongly reduced. Existing taxonomic concepts are mainly based on the variable morphological characters of shape and size of pitcher and lid, as well as on the number and length of anthers and the distribution and size of the retrorse hairs on the internal pitcher surface (Berry et al., 2005; Steyermark, 1984; Maguire, 1978).

The unique, isolated distribution of the genus on the remote and quite inaccessable table mountain plateaus (tepuis) of the Venezuelan Guayana, and therefore a rather poor collection history of the genus, as well as the lack of stable morphological characters for a suitable species delimination were the main reasons for the poverty of taxonomical work on Heliamphora (Steyermark, 1984; Maguire, 1978; Steyermark, 1951).

The aims of my studies were to investigate the deliminations and phylogenetic relationships of all known species of Heliamphora using molecular sequence data, to compare the results with the morphology-based species concepts proposed for the genus (Steyermark, 1984; Maguire, 1978), and to infer the origin and biogeographic distribution of Heliamphora, as well as the evolution of chromosome numbers (Fleischmann et al., in prep.).

Literature

Berry P.E., Riina R. & J.A. Steyermark (2005): Sarraceniaceae. In: Steyermark J.A., Berry P.E., Yatskievych K. & B.K. Holst (Eds.): Flora of the Venezuelan Guayana - Volume 9. Missouri Botanical Garden, USA.

Fleischmann A., Wistuba A. & J. Nerz (2009): Three new species of Heliamphora (Sarraceniaceae) from the Guayana Highlands of Venezuela. Willdenowia 39 (2): 273 – 283.

Maguire B. (1978): Sarraceniaceae, in: The Botany of the Guayana Highland - Part X. Memoirs of the New York Botanical Garden 29: 36 – 62.

Steyermark J.A. (1951): Botanical Exploration in Venezuela - 1. Fieldiana: Botany 28 (1): 239 – 242.

Steyermark J.A. (1984): Venezuelan Guayana. Annals of the Missouri Botanical Garden 71: 302 – 312.