Description from Flora of China
Herbs annual, usually covered with dendroid and stellate hairs. Leaves flat or flattened, filiform or linear to lanceolate, margin entire; veins 1-3. Flowers solitary in bract axils, bisexual, forming dense or loose, spikelike inflorescences on upper stem and branches; bractlets absent. Perianth segments 1-3 or absent, unequal, membranous, upper segment larger, lower 2 segments smaller or absent. Stamens 1-3 or 5; filaments linear, flattened, usually longer than perianth; anthers oblong, 2-loculed, longitudinally dehiscent. Ovary ovoid or ellipsoid, compressed; style short; stigmas 2. Fruit a utricle, compressed, oblong to orbicular in outline, abaxially convex, adaxially plane or slightly concave, margin usually winged, entire or erose, plane or crisped, apex emarginate or rounded to acute, beaked; beak with a 2-fid tip formed from style bases; pericarp adnate to seed. Seed vertical; embryo horseshoe-shaped; radicle inferior; perisperm copious.
Despite several attempts at regional taxonomic revisions, representatives of this taxonomically complicated genus are still insufficiently known in China. Several entities (species and varieties) are reported in China from only one to several localities and probably represent local forms of more widespread, variable species. Characters used for segregation of some species and infraspecific entities are very unreliable and variable (e.g., plant size, branching habit, degree of pubescence, color, shape of inflorescence etc.). For example, young plants are normally more pubescent than old ones, which sometimes become nearly glabrous at maturity. Many plants at maturity become yellowish or reddish to deep beet-red, which often greatly depends on environmental conditions. The branching habit depends, among other factors, on the populational structure: plants in dense stands are often less branched than plants growing in rarefied populations. The most reliable diagnostic characters are those of utricles; however, even these characters should be used carefully. When collecting Corispermum, representative series of specimens showing variability patterns and possible hybridization processes in populations are very desirable.
The number of species of Corispermum occurring in China is probably exaggerated. Variability ranges and hybridization patterns of taxa are also poorly understood. To reveal these peculiarities of Corispermum species in China, field observation and populational and experimental studies are desirable, with comparative data on Corispermum from adjacent territories.
In our opinion, the best solution at the present state of our knowledge of Corispermum in China would be to refrain from hasty decisions and attempts to reduce the number of taxa by uniting poorly known entities. Because of that, the present treatment mainly follows the treatment by Tsien and Ma in FRPS (1979), especially in the key and descriptions. However, we have inserted necessary taxonomic and nomenclatural comments drawing attention to particular problems.
About 60 species: N hemisphere, mostly in Asia, but several species in Europe and North America; 27 species (12 endemic) in China.