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petalidium

{{Short description|Genus of plants}}

{{Automatic taxobox

| name = Petal-bushes

| image = Petalidium oblongifolium, blom, Voortrekkerbad, c.jpg

| image_caption = P. oblongifolium flower with veined, cuspate bracteoles

| display_parents = 2

| taxon = Petalidium

| authority = Nees (1832)

| synonyms = Pseudobarleria {{small|T.Anderson (1863), nom. illeg.}}

| synonyms_ref = [https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:803-1 Petalidium Nees]. Plants of the World Online. Retrieved 7 February 2024.

}}

Petalidium, commonly known as petal-bushes, is a genus of perennial shrubs in the acanthus family.{{cite web|last1=van Jaarsveld |first1=Ernst |title=Petalidium bracteatum Oberm. |url=http://www.plantzafrica.com/plantnop/petalbract.htm |website=plantzafrica |publisher=Kirstenbosch NBG, SANBI |access-date=23 June 2015}} They are native to sandy flats or stony slopes in the drier bush regions of Africa, India and the Mascarene Islands.{{cite journal |last1=Clarke |first1=C. B. |title=Petalidium Nees |journal=Flora Capensis, Kew Gardens |date=1912 |volume=5 |page=1 |jstor=011354 }} The majority of species occur in frost-free, summer rainfall regions of southern Africa,{{cite web |last1=van Jaarsveld |first1=Ernst |title=Petalidium coccineum S.Moore |url=http://www.plantzafrica.com/plantnop/petalidcocc.htm |website=plantzafrica |publisher=Kirstenbosch NBG, SANBI |access-date=23 June 2015}} and may be found from low to medium altitudes.

Description

They have a diverse habit, forming either small, scrambling herbs or large, robust shrubs. Their dilated, tubular flowers are solitary or on short racemes growing from the leaf axils, and vary from white to mauve or red in colour. The four stamens are partially fused with the corolla, and the style is branched into two unequal parts. The calyx is deeply divided into five segments.

Two large, ovate to elliptic bracteoles subtend and protect the young corolla. The persistent bracteoles may be conspicuously veined or covered by long, villous trichomes. The small, ellipsoid fruit capsules explosively release two to four flat seeds (two ovules per ovary cell) when moisture is absorbed by their hygroscopic hairs. Young foliage and branches are covered in gland-tipped hairs. The leaves are entire.

Cultivation

Some species are cultivated as ornamentals, as they grow fast and flower profusely.

Etymology

According to Jackson (1990),{{cite journal|last1=Jackson|first1=W. P. U.|title=Origins and meanings of names of southern African plant genera|journal=Ecolab, Botany Department, University of Cape Town|date=1990}} the name Petalidium is derived from the Greek petalon (a leaf or petal), which may refer to the deciduous, leaf-like bracts, while bracteatum likewise refers to the large, imbricate (i.e. overlapping) bracts.

Species

There are 41 species in all, of which 29 occur in southern Africa.{{cite journal |last1=Germishuizen |first1=G. |last2=Meyer |first2=N. L. |title=Plants of southern Africa: An annotated checklist |journal=Strelitzia |date=2003 |volume=14 |pages=1–1231 |url=http://posa.sanbi.org/intro_posa.php |access-date=23 June 2015}} The species include:

References

{{Reflist}}

External links

  • [http://plants.jstor.org/stable/10.5555/al.ap.flora.flota007971 Petalidium Nees], Flora of Tropical Africa, Kew, Global Plants

{{Taxonbar|from=Q10348914}}

Category:Acanthaceae genera

Category:Taxa named by Christian Gottfried Daniel Nees von Esenbeck