Drosera peltata

Drosera peltata

Drosera peltata is an erect tuberous species native to the east coast of Australia. It is the type species of the convoluted and somewhat controversial species complex.

In the past, all erect sundews on the east coast of Australia was considered Drosera peltata. This complex of plants has been subject to various reviews, which define varying numbers of taxa. (For a good review, refer to the ICPS article). As I understand it, Drosera auriculata and lunata are uncontroversially separated on the basis of their glabrous sepals. Drosera hookeri and gunniana form a separate complex of plants with strong basal rosettes and bottle shaped seeds. Drosera yilgarnensis is considered a Western Australian relative.

A contention lies in the distinction between Drosera peltata and gracilis. Drosera peltata was originally described from plants in the Sydney region by Thunberg in 1797. These plants are therefore Drosera peltata in the strict sense. Some authors consider that the type specimen for Drosera gracilis (from Arthur’s Lake in Tasmania) are identical to the Sydney plants and so consider Drosera gracilis to be a subspecies of Drosera peltata. Others make a distinction, mostly based on seed morphology, coloration and stature.

I am currently studying the differences between D. peltata and gracilis in the field. I am yet to observe the seed or sepals of Drosera gracilis, so I will withhold my judgement. Drosera peltata itself seems be morphologically variable, with a thin red form that grows alongside an olive scrambling form in Sydney (although these may represent yet another taxon).

My personal opinion is that Drosera peltata is a good example of the pitfalls of the biological species concept, given that countless intermediate and aberrant forms within the complex complicate attempts to sort them into discrete categorical taxa. In reality, the plants were once all a single common ancestor, which radiated into different morphologies as they diverged into different niches. Where you draw the line to separate one ‘species’ from another is somewhat arbitrary especially when the differences occur on a spectrum.

Drosera peltata, as originally described, grows in heathy sandstone substrates within the Sydney region and surrounds. A basal rosette is sometimes absent or reduced in flowering sized plants. The species has a slender stem and crescent shaped leaves, both usually coloured olive green to bronze in good light. The inflorescence is held with considerable distance between the last set of leaves. The sepals are somewhat variable but are ovate-elliptical and hairy. The sepal hairs of the plants in Northern Sydney are thick and mostly do not have glands at their tip. I have not observed the seed in person. The plants are tall, growing over 30 cm and are usually self supporting or lean on surrounding vegetation.

Drosera peltata in northern Sydney
Drosera peltata northern Sydney
Drosera peltata northern Sydney
Drosera peltata central coast
Drosera peltata central coast.
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