| Hypericum decaisneanum | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Rosids |
| Order: | Malpighiales |
| Family: | Hypericaceae |
| Genus: | Hypericum |
| Section: | Hypericumsect. Adenosepalum |
| Species: | H. decaisneanum |
| Binomial name | |
| Hypericum decaisneanum | |
 | |
| Hypericum decaisneanum is found in theJebel al Akhdar province of Libya.[1] | |
| Synonyms[1] | |
Hypericum decaisneanum is a species offlowering plant in the St John's wort familyHypericaceae. Named for French botanistJoseph Decaisne, it is a smallperennialherb that grows mostly upright. It has thick, papery leaves and up to twenty flowers with bright yellowpetals.Endemic to theJebel al Akhdar province of Libya,H. decaisneanum is found in the cracks oflimestone rocks on steepescarpments. It is a member of numerousplant communities andassociations ofchasmophytes, of which it is sometimes akey species. Firstdescribed in 1899, the species was originally placed insectionTaeniocarpium of the genusHypericum, but more recently it has been considered a member ofsectionAdenosepalum.
Hypericum decaisneanum is aperennialherb that grows mostly upright and can be 4–15 centimetres (1.6–5.9 inches) tall. The base of the plant can have visible roots, and itstaproot is woody. It has many stems, but has no branches below itsflower clusters.[2]
The stems are covered in whitish-grey hairs, and are green on the upper parts of the plant and reddish on the lower parts. The leaves are crowded together and lack leaf stalks. The leaf blades are an oval shape, 0.6–1.2 cm (0.24–0.47 in) long and 0.4–1.0 cm (0.16–0.39 in) wide. They are the same color on the top and bottom, and have a thick, papery texture without any waxy coating. They have short hairs on their top side, and more dense hairs on the bottom. The leaf tip sometimes curls and is only somewhat pointed. There is no texture on the edges of the leaf, and the base is blunt. The leaf blades have a dense concentration of paleglands, and sometimes have a few black glands.[2]
The flower clusters have between three and twenty flowers out of 1–4 distinctnodes. There are no flowering branches on the lower parts of the stem; all flowers are in a narrow pyramid-shaped orcorymb-like cluster at the end of the stem. Thebracts and bracteoles range in shape from stretched ovals to triangularlances, and have dense black glands. Individual flowers are around 1.2–1.5 cm (0.47–0.59 in) wide, and are an egg shape whenbudding. Thesepals are 0.3–0.5 cm (0.12–0.20 in) long and 0.1 cm (0.039 in), but are usually around the same size on a flower. They range in shape from narrow andoblong to wide andelliptic, with a rounded end. They have pale glands in linear patterns, and sometimes several black dots near their end. The petals are bright yellow with red veins, and measure 0.6–0.8 cm (0.24–0.31 in) long and 0.3 cm (0.12 in) wide, or roughly 2.5 times the size of the sepals. They are oblong and have a rounded tip, rather than a pointed tip orapiculus. There may or may not be scattered pale and black glands on the petals. Each flower has around 40stamens, the longest of which are 0.5–0.7 cm (0.20–0.28 in), or just shorter than the petals, and have a blackanther gland. Theovary has the shape of a narrow, egg-like pyramid, withstyles that are around 0.3–0.6 cm (0.12–0.24 in) long and curve inwards. Theseed capsule is egg-shaped, and can be larger than the sepals. While the seed capsule is immature, it is enclosed by the petals which twist around each other.[2]
Hypericum decaisneanum blooms in the late spring and early summer.[3] In general, because of its dense and hairy leaves and the black glands on its petals, the species resembles a smaller form ofHypericum annulatum subsp.afromontanum.[2]
One origin of thegenus nameHypericum is that it is derived from theGreek wordshyper (above) andeikon (picture), in reference to the tradition of hanging the plant over religiousicons in the home.[4] Thespecific epithetdecaisneanum is in honor of French botanistJoseph Decaisne, who was a supporter of an expedition to collect the species.[5]
The species was originallydescribed byErnest Cosson andJules Alexandre Daveau in 1899 asHypericum decaisneanum.[1] In the description they listed the unresolved nameH. taubertii as asynonym of the species, but did not provide reasoning for the inclusion.[6][7] Cosson and Daveau placedH. decaisneanum insectionTaeniocarpium based on theirmorphological observations.[5] While most species of the genusHypericum were included in amonographic study byNorman Robson in the 20th century,H. decaisneanum was not mentioned. Furthermore, its closest relatives were later addended to the monograph, and their infrageneric relationships were discussed.[a][8] However,H. decaisneanum was neglected from the later editions of the monograph as well.[8] In an online edition of the monograph published in 2013, the species was included by Norman Robson and his colleague David Pattinson within a "Huber-morathii group" inside sect.Adenosepalum. Under that classification, the placement ofHypericum decaisneanum was summarized as follows:[2]
Hypericum decaisneanum isnative to theJebel al Akhdar province of Libya.[1] It is found in the crevices oflimestone rocks at elevations of 20–700 metres (66–2,297 feet).[2] In particular, it is found on the north-facing slopes of majorescarpments.[9]
Hypericum decaisneanum belongs toplant communities that have been the subject of several research endeavors. It has been noted to be part of an association ofchasmophytes that centers aroundMicromeria conferta andReaumuria mucronata.[b][10] It is also a part of onespecies association called "Athamantion dellae-cellae",[c][11] and is a key species in another alliance called "Sedo micranthi-Hypericetum decaisneani" along withSedum album and other chasmophytes.[d][12]
Like other species in theHuber-morathii group,[13]H. decaisneanum can becultivated in dry, rocky crevices with poor soil and protection against winter wetness. It can bepropagated by seeding in spring under a thin layer of soil, and has agermination period of 1–3 months.Cuttings are taken in the late summer.[3]