Comesperma is a genus of approximately 38 species of shrubs, herbs, and lianas in the family Polygalaceae (order Fabales), endemic to Australia. The genus was established by French botanist Jacques Labillardière in his 1806 work Novae Hollandiae Plantarum Specimen and represents one of the more distinctive Australian members of the milkwort family.
Plants are generally small shrubs, climbers, or trailing herbs with small to vestigial leaves arranged alternately along the stems. The flowers closely resemble those of pea-flowers and are borne in racemes. They range in colour from pink through shades of purple to blue, though yellow-flowered species also occur. While individual flowers are smaller than those of the related genus Polygala, the racemes can be quite showy, particularly in floriferous species such as Comesperma ericinum (heath milkwort or pyramid flower).
The genus is distributed across southern Australia, with the greatest concentration of species in the southwest of Western Australia, where 19 species occur. Comesperma calymega (blue-spike milkwort), C. volubile (love creeper), C. ericinum, and C. drummondii (Drummond's milkwort) are among the better-known members. Comesperma ericinum and C. volubile are occasionally grown in cultivation.
Taxonomically, the genus was placed in the tribe Polygaleae by Swiss botanist Robert Hippolyte Chodat in 1896. A brief proposal by van Steenis (1968) to subsume it within Bredemeyera was not widely adopted. A 1993 morphology-based cladistic analysis supported its recognition as a distinct genus, resolving it as basal to a clade containing Polygala, Monnina subg. Monninopsis, Nylandtia, Muralita, and Epirixanthes.
Etymology
The genus name Comesperma derives from the Ancient Greek come ("hair") and sperma ("seed"), a reference to the characteristic tufts of hair borne on the seeds. The name was coined by Jacques Labillardière in 1806.
Distribution
Comesperma is endemic to Australia, distributed across the southern part of the continent. The greatest species richness occurs in the southwest of Western Australia, which harbours 19 of the approximately 38 accepted species. Smaller numbers of species extend into southeastern Australia.
Taxonomy
The genus was established by Jacques Labillardière in 1806 and classified in tribe Polygaleae (family Polygalaceae) by Chodat in 1896. Van Steenis (1968) proposed treating it as a section of Bredemeyera, but this was not widely followed. A 1993 cladistic study based on morphology reaffirmed Comesperma as a distinct genus, placing it as basal to a clade including Polygala, Monnina subg. Monninopsis, Nylandtia, Muralita, and Epirixanthes.
