Sea spider iris  (Ferraria crispa)

Subspecies Ferraria crispa nortieri is classified as Vulnerable (VU) and Ferraria crispa crispa is classified as Least Concern (LC) on the Interim Red Data List of South African Plant Taxa (4).

The sea spider iris is distinctive for the unusual flowers it bears and the acrid scent of rotting flesh it emits. The brown or yellowish, speckled flowers measure around 30 millimetres across and the petals have crispy margins, hence the scientific name of this species, crispa (5). The leaves of the sea spider iris are sword-shaped and slightly fleshy (3) (5), and they partly cover the branched, straight or slightly twisted stem (6). A swollen stem base of the sea spider iris forms an underground storage organ, or corm, which stores food for the plant (3) (7).

Endemic to the Cape Floristic Region, a ‘hot-spot’ of plant diversity in south-western South Africa. The sea spider iris is distributed from Lamberts Bay, south and east to Mossel Bay (3).

The sea spider iris mainly inhabits coastal areas, where it grows on sandstone or granite rocks (3).

The sea spider iris bears its pungent, peculiar flowers between August and October (3), but each flower lasts for just a single day (6). Little information is available regarding the biology of the sea spider iris, but it can be presumed to be similar to that of other Ferraria species. Ferraria species are known to be pollinated by dung, flesh and game flies, and also by bees and wasps. The dull, mottled patterning of the flowers, along with their unpleasant rotting flesh or fermenting fruit scent attract flies (1), who are duped into thinking this is a suitable place to lay eggs (8). The flies walk all over the flowers trying, and failing, to find a suitable place to lay their eggs (8), and leave dusted liberally with bright orange pollen. While the sea spider iris does not provide insects with a suitable place to lay eggs, pollinators are rewarded with sips of concentrated nectar (1).

The subspecies F. c. nortieri is classified as Vulnerable (4), but at present there is no information available to indicate what specific threats this species faces. However, as it is restricted to the Cape Floristic Region, it is likely to be impacted by urban development, the encroachment of agriculture and the invasion of alien species, threats that are known to be affecting the region’s habitat and numerous endemic plant species (9) (10).

Within the Cape Floristic Region there are a number of protected areas (11), and a number of conservation organisations are working to conserve the botanically rich habitat of the Cape Floristic Region. Conservation actions include purchasing land to protect it from the threats of encroaching agriculture and urban development (12), the removal of alien plants, and the establishment of new protected areas (10); measures which should benefit the vulnerable subspecies F. c. nortieri.

For further information on the Cape Floristic Region and its conservation see:

• Conservation International: Biodiversity Hotspots:
  www.biodiversityhotspots.org/xp/hotspots/cape_floristic