Othonna

Othonna
Othonna capensis
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Asterids
Order:	Asterales
Family:	Asteraceae
Tribe:	Senecioneae[1]
Genus:	Othonna L. (1753)
Type species
Othonna coronopifolia[2] L.
Synonyms[1]
Doria Thunb. Ceradia Lindl. Calthoides B.Juss. ex DC. Aristotela Adanson

Othonna is a genus of African plants in the sunflower family.^[3][2]

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]

References

External links

• Othonna 1998-2004 Philippe Faucon. Retrieved on February 5, 2007.
• African succulents 2003 African Succulents. Retrieved on February 5, 2007.