Othonna
Othonna is a genus of African plants in the sunflower family.[3][2]
| Othonna | |
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| Othonna capensis | |
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| Genus: | Othonna |
| Type species | |
| Othonna coronopifolia[2] | |
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These are evergreen or deciduous geophytes, dwarf succulents or shrubs concentrated in the Western Cape Province of South Africa and also in southern Namibia. A few species occur in summer rainfall parts of southern Africa. The genus is closely allied to Senecio and can be distinguished principally by details of the involucre. Taxonomically, they are in need of a modern revision.
The form or habit of othonnas is very diverse and in this lies much of their appeal to collectors of winter growing succulent plants. The various species may be pachycauls with elongate but proportionately swollen stems, caudiciform caudiciforms or dwarf and compact succulents with short branches. A highly distinctive group is made up tuberous geophytes with subterranean rootstocks and deciduous stems or leaves. Other species are orthodox shrubs.
Leaf diversity is also notable in this genus. A few species possess highly succulent leaves (e.g., O. capensis, O. sedifolia) but most have bifacial leaves that are only slightly succulent. Size and shape is variable, with most species having leaves in the 1–10 cm long range, common shapes being elliptic, lanceolate, oblanceolate or spathulate. The leaf blades may be intricately divided (O. abrotanifolia) or lobed (O. cakilaefolia), amplexicaul or distinctly undulate. Often the leaves are sessile and the lamina is glaucous; leaf margins are entire to coarsely toothed. Some species are dimorphic in that the acaulescent juvenile leaves are very different from the adult leaves that are produced on the flowering stems.
With few exceptions the flowers of othonnas fit the stereotypical "DYC" ("Damned Yellow Composite", a tongue-in-cheek phrase used for a variety of composites) designation. A simple or branched inflorescence gives rise to daisy-like flower heads. The exceptions are a handful of attractive purple-flowered species that are deciduous geophytes. Most if not all species are self-incompatible. The seeds are often proportionately heavy and probably do not travel far from the parent plant without the assistance of brisk winds. In at least some cases the seeds exude a sticky substance when wetted and thus affix themselves to the soil surface, aiding in the establishment of seedlings.
- Species[1]
- Othonna abrotanifolia
- Othonna acutiloba
- Othonna alata
- Othonna alba
- Othonna amplexifolia
- Othonna arborescens
- Othonna arbuscula
- Othonna armiana
- Othonna auriculifolia
- Othonna brandbergensis
- Othonna bulbosa
- Othonna burttii
- Othonna cacalioides
- Othonna cakilefolia
- Othonna campanulata
- Othonna capensis
- Othonna carnosa
- Othonna chromochaeta
- Othonna ciliata
- Othonna clavifolia
- Othonna coronopifolia
- Othonna cuneata
- Othonna cyclophylla
- Othonna cylindrica
- Othonna decurrens
- Othonna dentata
- Othonna digitata
- Othonna divaricata
- Othonna diversifolia
- Othonna elliptica
- Othonna eriocarpa
- Othonna euphorbioides
- Othonna filicaulis
- Othonna floribunda
- Othonna frutescens
- Othonna furcata
- Othonna graveolens
- Othonna gymnodiscus
- Othonna hallii
- Othonna hederifolia
- Othonna herrei
- Othonna heterophylla
- Othonna huillensis
- Othonna humilis
- Othonna incisa
- Othonna intermedia
- Othonna lasiocarpa
- Othonna laureola
- Othonna lepidocaulis
- Othonna leptodactyla
- Othonna lineariifolia
- Othonna lingua
- Othonna lobata
- Othonna lyrata
- Othonna macrophylla
- Othonna macrosperma
- Othonna membranifolia
- Othonna mucronata
- Othonna multicaulis
- Othonna nana
- Othonna natalensis
- Othonna nodulosa
- Othonna obtusiloba
- Othonna oleracea
- Othonna opima
- Othonna osteospermoides
- Othonna ovalifolia
- Othonna pachypoda
- Othonna papaveroides
- Othonna parviflora
- Othonna patula
- Othonna pavelkae
- Othonna pavonia
- Othonna perfoliata
- Othonna petiolaris
- Othonna pinnata
- Othonna plantaginea
- Othonna pluridentata
- Othonna primulina
- Othonna protecta
- Othonna pteronioides
- Othonna purpurascens
- Othonna pygmaea
- Othonna quercifolia
- Othonna quinquedentata
- Othonna quinqueradiata
- Othonna ramulosa
- Othonna rechingeri
- Othonna reticulata
- Othonna retrofracta
- Othonna retrorsa
- Othonna rhamnoides
- Othonna rosea
- Othonna rotundifolia
- Othonna rufibarbis
- Othonna sedifolia
- Othonna semicalva
- Othonna sonchifolia
- Othonna sparsiflora
- Othonna spinescens
- Othonna stenophylla
- Othonna taraxacoides
- Othonna tephrosioides
- Othonna tortuosa
- Othonna trinervia
- Othonna triplinervia
- Othonna umbelliformis
- Othonna vestita
- Othonna viminea
- Othonna whyteana
- Othonna zeyheri
References
External links
- Othonna 1998-2004 Philippe Faucon. Retrieved on February 5, 2007.
- African succulents 2003 African Succulents. Retrieved on February 5, 2007.