Protea decurrens, also known as linear-leaf sugarbush, is a shrub of the genus Protea, in the Proteaceae family, which is endemic to the southwestern Cape Region of South Africa. It is a small shrub with a thick underground rootstock, this structure throwing up numerous leafy branches, upon the base of which clusters of flower heads may appear close to the ground. It is pollinated by rodents and grows in low-altitude fynbos or renosterveld.
In the Afrikaans language it is known as the Overbergsesuikerbos.
Taxonomy
It was first described as a new species by Edwin Percy Phillips in 1910, but the plant was known long before Phillips. In the Prodromus of 1856, under the name Protea humilis, Carl Meissner is thought to have actually partially described this species (i.e. a synonym pro parte), based on the herbarium specimen he was using, which had recently been collected by the German explorer Karl Ludwig Philipp Zeyher.
P. humiflora has a confused history. The plant had first been described by Henry Cranke Andrews using the spelling P. humiflora in his magazine The Botanists' Repository. In describing the plant, he made use of a living specimen blooming at the estate of the Protea collector George Hibbert, yet his illustration is somewhat confused in arrangement of the flower heads on the plant, showing a plant with the heads clustered on the stem near the ground and purplish in colour more like P. decurrens, where as the herbarium specimens of the same plant show this not to be the case. The seeds and specimens had first been collected by Francis Masson and one Drummond, and according to Stapf the Drummond specimen was actually P. decurrens. Spelled as P. humilis, it was described in Robert Brown's 1810 work in On the Proteaceae of Jussieu, with Andrews' older name designated a synonym and only the Masson specimen mentioned with regards to type. According to Meissner, by the mid-19th century, in horticultural collectors' circles, there were plants -possibly two or more species- which were grown, traded and sold under the name P. humifusa on the European continent, and he also reports Carl Ludwig Willdenow used the spelling P. humiflorens. Meissner in 1856 advocated the use of Brown's name, despite it being a homotypic synonym, a decision opposed by Phillips in 1910 and Stapf in 1912. Thus by the 1910s a P. humiflora was known to exist, and had been recollected in South Africa by William John Burchell and later Rudolf Marloth around the turn of the previous century.
Types
Stapf designated the holotype of this species to be the afore-mentioned P. humiflora specimen collected by Drummond in the 18th century; it is without a precise collection locale, and is likely lost. In the 19th century the species was collected again by Zeyher, and later the South African Harry Bolus, both in the mountains in the area of Swellendam. Zeyher gives two, possibly three, locations near Swellendam, and he apparently also collected it somewhere along the banks of a place he called the 'Keurboom Rivier', which according to Phillips was in what in his time was the Knysna Division. The original herbarium sheet has all of these localities on the label of his specimen 3676. This effectively might mean that Zeyher 3676 is composed of a number of different plants from different localities (a type series), thus in 1972 the South African botanist John Patrick Rourke, considering the lack of the Drummond specimen, designated the Zeyher specimen sheet extant at the Kew Herbarium as a syntype.
Etymology
The species epithet refers to its decurrent leaves.
Description
Protea decurrens grows up to 50 cm in diameter and 60 cm in height. It is suffrutescent; the main trunk of the plant is found burrowing below the ground like a thick root, sending up a number of branches which can grow from prostrate on the ground to ascending. The plant flowers from the base of these branches at ground level.
The linear to acicular-shaped leaves are 1.4mm in width, but in length. The leaves are glabrous, end in a point, and are shortly decurrent: their bases partially clasp the stem.