Untangling the sand lilies - a new classification

Sand lilies, in the Daylily family, are not the most conspicuous elements of the Australian flora, but they are very intriguing for a number of reasons.

Corynotheca micrantha, a common species on the Swan Coastal Plain. Photo: Russell Barrett.

A taxonomic revision of the genus Corynotheca recognises thirteen species, up from six species and five varieties in previous classifications. Sand lilies are distributed over most of Australia, but oddly, they are absent from the east.

Distribution of Corynotheca species. Map A (left): C. borealis (orange); C. divaricata (blue); C. gracilis (red); C. flexuosissima (green); C. lateriflora (pink). Map B (centre): C. asperata (red); C. dichotoma (pink); C. licrota (blue); and C. micrantha (green). Map C. C. acanthoclada (red); C. elongata (green); C. panda (pink); and C. pungens (blue). Maps based on data from the Australian Virtual Herbarium.

Found only in Australia, the highest number of species are found in the south-west of Western Australia, a biodiversity hotspot. The next area of diversity is the arid interior, and three species occur in the northern monsoon tropics.

Our studies showed that named varieties they were all more appropriately recognised as species. We also reinstated a long-forgotten species from the mid-west of WA, and described a new species from the WA/NT border region in the far-north.

Most sand lilies appear to be leafless, as the few leaves they do produce at the start of each season quickly wither in most species. Their real stems are also entirely underground, where they are protected from fire and drought

Key features used in descriptions and for identification of Corynotheca species.

What we see above-ground is actually all flower stalk, or inflorescence. These are green, taking on the role of the photosynthetic organ of the plant in the absence of green leaves or stems. These inflorescences present some rather intriguing patterns, providing useful characters for identification.

Flowering inflorescence of Corynotheca divaricata. Photo: Russell Barrett.

The 'stems' angle away from each other to varying degrees at each node, so the plants usually have a very tangled appearance. Some species angle at about 60 degrees, and so form neat hexagons in repeating patterns.

Intricate branching patterns in Corynotheca flexuosissima. Photos: Russell Barrett.

The small white flowers are visited by a range of small insects and a few species are sweetly scented, offering minute amounts of nectar to their visitors. The flowers usually only open for a few hours, when conditions are optimal for pollinators to be flying.

Flowers of Corynotheca divaricata. Photos: Russell Barrett.

The shiny black seeds often have a wrinkled surface, reminiscent of a fingerprint. They also have some odd attachments, which can look like horns or antlers, and a small white frill that attracts ants for seed dispersal, called an eleiosome. Seeds are only produced in good seasons, and fall quickly once ripe, and have never been seen in one rarely seen species from the Great Sandy Desert.

Fruit and seeds of Corynotheca lateriflora. Photos: Russell Barrett.

As their name suggests, sand lilies grow in sandy places, and in the Australian interior, they are most commonly encountered on the top of sand dunes. Others are common in sandy woodlands, such as Banksia woodlands in Kings Park, in the heart of Perth.

Most species are endemic (restricted) to a single biographical region, so their relationships are of interest in understanding the evolution of Australia's flora. A Masters student at Melbourne University, Aiden Webb, is currently investigating the evolution of this genus using DNA data.

The poorly known species Corynotheca acanthoclada has been redefined and it is now recognised to be highly localised between Kalbarri and Mingenew in Western Australia. Photo: Jennifer Jackson.

The paper revising Corynotheca is available for free in the New South Wales National Herbarium journal Telopea:

Barrett, R.L., Macfarlane, T.D. & Keighery, G.J. (2021) Taxonomic revision of Corynotheca (Hemerocallidaceae / Asphodelaceae). Telopea24: 7–52. PDF