''Petalidium'', commonly known as petal-bushes, is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of perennial shrubs in the acanthus family. They are native to sandy flats or stony slopes in the drier bush regions of

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and the

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. The majority of species occur in frost-free, summer rainfall regions of

southern Africa Southern Africa is the southernmost subregion of the African continent, south of the Congo and Tanzania. The physical location is the large part of Africa to the south of the extensive Congo River basin. Southern Africa is home to a number of ...

, 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 Corolla may refer to: *Corolla (botany), the petals of a flower, considered as a unit *Toyota Corolla, an automobile model name * Corolla (headgear), an ancient headdress in the form of a circlet or crown * ''Corolla'' (gastropod), a genus of moll ...

. 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 Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance ...

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), 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 more than 30 species in all, of which 29 occur in southern Africa. The species include: * '' Petalidium angustitubum'' P.G. Mey. * '' Petalidium aromaticum'' Oberm. – n South Africa, s Zimbabwe * '' Petalidium barlerioides'' (Roth) Nees * '' Petalidium bracteatum'' Oberm. – s Angola?, n & c Namibia * '' Petalidium canescens'' C.B. Clarke * '' Petalidium cirrhiferum'' S.Moore * '' Petalidium coccineum'' S.Moore – nw Namibia * ''

Petalidium crispum ''Petalidium'', commonly known as petal-bushes, is a genus of perennial shrubs in the acanthus family. They are native to sandy flats or stony slopes in the drier bush regions of Africa, India and the Mascarene Islands. The majority of species o ...

'' A. Meeuse ex P.G. Mey. * '' Petalidium currorii'' S.Moore – Angola * '' Petalidium cymbiforme'' Schinz * '' Petalidium giessii'' P.G. Mey. * '' Petalidium glandulosum'' S.Moore * '' Petalidium gossweileri'' S.Moore * '' Petalidium halimoides'' (Nees) S.Moore – Namibia * '' Petalidium huillense'' C.B.Clarke * '' Petalidium lanatum'' C.B. Clarke * '' Petalidium lepidagathis'' S.Moore * ''

Petalidium linifolium ''Petalidium'', commonly known as petal-bushes, is a genus of perennial shrubs in the acanthus family. They are native to sandy flats or stony slopes in the drier bush regions of Africa, India and the Mascarene Islands. The majority of species o ...

'' T. Anderson * ''

Petalidium lucens ''Petalidium'', commonly known as petal-bushes, is a genus of perennial shrubs in the acanthus family. They are native to sandy flats or stony slopes in the drier bush regions of Africa, India and the Mascarene Islands. The majority of species o ...

'' Oberm. * ''

Petalidium luteo-album ''Petalidium'', commonly known as petal-bushes, is a genus of perennial shrubs in the acanthus family. They are native to sandy flats or stony slopes in the drier bush regions of Africa, India and the Mascarene Islands. The majority of species o ...

'' A. Meeuse * ''

Petalidium oblongifolium ''Petalidium'', commonly known as petal-bushes, is a genus of perennial shrubs in the Acanthaceae, acanthus family. They are native to sandy flats or stony slopes in the drier bush regions of Africa, India and the Mascarene Islands. The majority ...

'' C.B. Clarke – South Africa * '' Petalidium ohopohense'' P.G. Mey. * '' Petalidium physaloides'' S.Moore – Namibia * '' Petalidium pilosi-bracteolatum'' Merxm. & Hainz – Namibia * '' Petalidium ramulosum'' Schinz * '' Petalidium rautanenii'' Schinz * '' Petalidium rossmannianum'' P.G. Mey. * '' Petalidium rupestre'' S.Moore * '' Petalidium setosum'' C.B. Clarke ex Schinz – n, c & s Namibia * '' Petalidium spiniferum'' C.B.Clarke – Chella Mountains, Angola * '' Petalidium subcrispum'' P.G. Mey. * '' Petalidium tomentosum'' S.Moore * '' Petalidium variabile'' C. B. Cl. Hybrid * '' Petalidium welwitschii'' S.Moore

References

External links

Petalidium Nees
Flora of Tropical Africa, Kew, Global Plants * {{Taxonbar, from=Q10348914 Acanthaceae genera