Johnsonia (plant)
| Johnsonia | |
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| Johnsonia pubescens in Lesueur National Park, Western Australia | |
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| Genus: | Johnsonia |
| Type species | |
| Johnsonia lupulina | |
| Diversity | |
| five species (see text) | |
Johnsonia is a genus of herbs in the family Xanthorrhoeaceae. They are grass-like plants with minute flowers surrounded by bracts which are often tinged with white, pink or cream. There are five species, all of which are endemic to the south-west of Western Australia.[1]
Description
All the plants in this genus are rhizomatous, tufted, perennial herbs with grass-like leaves which all emerge from the base of the plant. The bases of the leaves surround the stem. The flower spike is leafless, more or less the same length as the leaves, with large, dry overlapping bracts surrounding minute flowers. All species flower between August and December.[2][3]
Taxonomy and naming
The genus was first described in 1810 by R.Br. in Prodromus Florae Novae Hollandiae et Insulae Van Diemen. The type species is Johnsonia lupulina. The name Johnsonia is in recognition of the 17th century English naturalist, Thomas Johnson.[2]
It is most closely to four other genera confined to the south of Western Australia - Arnocrinum , Hensmania , Hodgsoniola and Stawellia. Johnsonia species differ from these in the shape of its leaves and by its long flower spikes with the flowers enclosed in large bracts.
- Species[1]
- Johnsonia acaulis Endl. in J.G.C.Lehmann, Pl. Preiss. 2: 41 (1846)
- Johnsonia inconspicua Keighery, Fl. Australia 45: 490 (1987)
- Johnsonia lupulina R.Br., Prodr. Fl. Nov. Holl.: 287 (1810)
- Johnsonia pubescens Lindl., Sketch Veg. Swan R.: 57 (1839)
- Johnsonia teretifolia Endl. in J.G.C.Lehmann, Pl. Preiss. 2: 40 (1846)
Distribution and habitat
Johnsonia species all occur in the south-west of Western Australia in the Avon Wheatbelt, Esperance Plains, Jarrah Forest, Mallee, Swan Coastal Plain and Warren biogeographic zones. Each species has its own habitat requirements.[4]
References
- ^ a b Kew World Checklist of Selected Plant Families
- ^ a b Keighery, Greg. "Johnsonia". Australian national botanic gardens - flora online. Retrieved 8 March 2015.
- ^ "Johnsonia R.Br". FloraBase. Western Australian Government Department of Biodiversity, Conservation and Attractions.
- ^ Paczkowska, Grazyna; Chapman, Alex R. (2000). The Western Australian flora : a descriptive catalogue. Perth: Wildflower Society of Western Australia. p. 32. ISBN 0646402439.
External sources
- Brown, Robert (1810). Prodromus florae Novae Hollandiae et Insulae Van-Diemen, exhibens characteres plantarum. London. p. 287. Retrieved 8 March 2015.
