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 occur in frost-free, summer rainfall regions of southern Africa, 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), 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. 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 (Engl.) C.B.Clarke Petalidium cirrhiferum S.Moore Petalidium coccineum S.Moore – nw Namibia Petalidium crispum A. Meeuse ex P.G. Mey. Petalidium currorii S.Moore – Angola Petalidium cymbiforme Schinz Petalidium elatum Petalidium englerianum Petalidium engoense - Angola, Namnibia 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 kaokoense Swanepoel – Namibia Petalidium lanatum C.B.Clarke Petalidium lepidagathis S.Moore Petalidium linifolium T.Anderson Petalidium lucens Oberm. Petalidium luteoalbum A.Meeuse Petalidium mannheimerae Petalidium microtrichum Petalidium oblongifolium C.B.Clarke – South Africa Petalidium ohopohense P.G.Mey. Petalidium parvifolium Petalidium physaloides S.Moore – Namibia Petalidium pilosibracteolatum 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 (Engl.) C.B.Clarke Petalidium welwitschii S.Moore
References
External links Petalidium Nees, Flora of Tropical Africa, Kew, Global Plants