Holcus (commonly known as soft-grass or velvetgrass) is a genus of flowering plants in the family Poaceae (Gramineae), placed in the oat tribe Aveneae. The genus belongs to the class Liliopsida (monocots) within the kingdom Plantae. GBIF recognises five accepted species in the genus.
The plants are native to Africa and Eurasia, with the two most widespread members — Holcus lanatus (Yorkshire fog) and Holcus mollis (creeping soft-grass) — having become extensively naturalized across temperate regions worldwide, including North and South America, Australia, and New Zealand. Several species have more restricted ranges: Holcus caespitosus is endemic to the Sierra Nevada of southern Spain, Holcus rigidus and Holcus azoricus are Azorean, and Holcus setiger is confined to the Cape Province of South Africa.
Holcus species are characterised by soft, often velvety herbage that gives rise to the common name velvetgrass. As grasses, they produce small wind-pollinated florets arranged in panicles. The genus has ecological significance as a food source for the larvae of several Lepidoptera species, including Coleophora lixella.
A number of species formerly placed in Holcus have been transferred to other genera, including Andropogon, Arrhenatherum, Deschampsia, Pennisetum, Sorghum, and others, reflecting revisions to grass systematics over time.
Distribution
Holcus is native to Africa and Eurasia. Holcus lanatus has the widest range, occurring from Iceland and the Canary Islands to the Caucasus, and is naturalized in North and South America, Australia, New Zealand, East Asia, and various oceanic islands. Holcus mollis is native to most of Europe and parts of North Africa (Algeria, Tunisia), and is naturalized in Australia, New Zealand, and scattered localities in North America.
Ecology
Holcus species serve as larval food plants for several Lepidoptera, including Coleophora lixella. Holcus lanatus and Holcus mollis are considered invasive or weedy grasses in regions where they are naturalized, often establishing in disturbed ground, roadsides, meadows, and pastures.
Taxonomy Notes
Several species historically placed in Holcus have been reassigned to other genera including Andropogon, Arrhenatherum, Arundinella, Bothriochloa, Capillipedium, Centotheca, Chasmanthium, Chrysopogon, Deschampsia, Heteropogon, Hierochloe, Pennisetum, Pentameris, Pseudoraphis, Rostraria, Sorghum, Sporobolus, and Ventenata. Holcus azoricus is possibly a hybrid of H. lanatus and H. rigidus; the confirmed hybrid H. × hybridus (H. lanatus × H. mollis) occurs in France, Germany, and the British Isles.
