''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
Africa
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
,
India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
and the
Mascarene Islands
The Mascarene Islands (, ) or Mascarenes or Mascarenhas Archipelago is a group of islands in the Indian Ocean east of Madagascar consisting of the islands belonging to the Republic of Mauritius as well as the French department of Réunion. Thei ...
.
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
''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 ...
'' S.Moore
* ''Petalidium gossweileri
''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 ...
'' S.Moore
* ''Petalidium halimoides
''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 ...
'' (Nees) S.Moore – Namibia
* ''Petalidium huillense
''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 ...
'' C.B.Clarke
* ''Petalidium lanatum
''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 ...
'' C.B. Clarke
* ''Petalidium lepidagathis
''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 ...
'' 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