Adenanthos obovatus

The growth habit of Adenanthos obovatus is that of a lignotuberous shrub, with many stems arising from a single underground lignotuber. It typically reaches about in height, and about in width, but plants occasionally reach a height of . The leaves of this species are bright green, oval in shape, up to long and wide, sessile, and arranged in a spiral pattern on the branches. They are red or orange, and emerge from the leaf axils. They are usually solitary, but occasionally an axil will carry two flowers. As with other Proteaceae species, each flower consists of a perianth of four united tepals, and a single style. In A. obovatus, the perianth is around long, and the style around . ==Taxonomy==

Discovery and naming 's 1805 Novae Hollandiae plantarum specimen. This figure accompanied the formal publication of A. obovata; its resemblance to a specimen collected by Jean Baptiste Leschenault de la Tour is taken as evidence that Leschenault is the unattributed collector of the type specimen. However, this collection did not result in publication of the species. Other early collections include a specimen collected by Scottish botanist Robert Brown during the visit of HMS Investigator to King George Sound in December 1801 and January 1802; and, thirteen months later, King George Sound specimens collected by Jean Baptiste Leschenault de la Tour, botanist to Nicolas Baudin's voyage of exploration, and "gardener's boy" Antoine Guichenot. In his notes on vegetation published in the official account of the expedition, Leschenault writes: The species with rounded leaves was A. obovatus. A description of the species was published by Jacques Labillardière in his 1805 Novae Hollandiae Plantarum Specimen, Labillardière chose the specific name obovata, in reference to the leaves of his specimen, which were obovate (egg-shaped, with the narrow end at the base). This leaf shape is often seen in this species. The term obovata derives from the Latin ob- ("inverse") and ovum ("egg"), and has feminine gender, consistent with the gender assigned by Labillardière to the genus. Labillardière did not acknowledge any collector, and so it was long thought that Labillardière himself had collected the first botanical specimens in 1792 while naturalist to Bruni d'Entrecasteaux's expedition in search of the lost ships of Jean-François de Galaup, comte de La Pérouse. However, this and eight other species described by Labillardière do not occur in any locations that he visited, suggesting that he obtained specimens from someone else whom he failed to credit. Though he did not specify a type specimen for A. obovata, a specimen upon which the accompanying figure in Novae Hollandiae Plantarum Specimen appears to be based has been located; it is annotated, apparently in Labillardière's hand, as having been collected by Leschenault. and this view has been accepted by some scholars though others treat it more cautiously. Infrageneric placement In 1870, George Bentham published the first infrageneric arrangement of Adenanthos in Volume 5 of his landmark Flora Australiensis. Bentham divided the genus into two sections, placing A. obovata in A. sect. Eurylaema, defined as containing those species with one sterile stamen, and perianth tubes that are curved and swollen above the middle. A phenetic analysis of the genus undertaken by Ernest Charles Nelson in 1975 yielded results in which the members of A. sect. Eurylaema occurred together, with A. obovata appearing most closely related to A. barbigera (now A. barbiger), and then A. detmoldii. A. obovata was therefore retained in A. sect. Eurylaema in Ernest Charles Nelson's 1978 revision of Adenanthos, and again in his 1995 treatment of the genus for the Flora of Australia series. By this time, the ICBN had issued a ruling that all genera ending in -anthos must be treated as having masculine gender. Hence the species is now known as Adenanthos obovatus. Its placement in Nelson's arrangement of Adenanthos may be summarised as follows: It is also possible that A. obovatus infrequently hybridises with A. barbiger: in 1921, Carl Hansen Ostenfeld described A. intermedia (now A. intermedius), based on specimens found near Ngilgi Cave at Yallingup with leaf shape intermediate between these two species. ==Distribution and habitat==

Abundant and widespread, A. obovatus occurs on a wide range of soils, favouring soils in the acidic pH range 3.9–5.4. Like most Adenanthos species it is common on deeply leached siliceous sandplain sand. It also occurs on gravelly quartz sand derived from rock outcrops, such as on the rocky hillslopes of the Stirling Range. It is rarely found on gravelly lateritic soils. It is also one of the few Adenanthos species to grow well in moist environments; it will not tolerate seasonal waterlogging—that niche is filled by A. detmoldii—but thrives in damp soils not subject to waterlogging. Consistent with these edaphic preferences, A. obovatus is widespread and common in the scrub and heath commonly found on the sandplains of Southwest Australia, and is also common in the sedgelands that develop in moister areas of the region. It is uncommon in forest or woodland areas, because these are usually associated with lateritic soils; but it may be found in stands of jarrah or marri forest where these grow in laterite-free sand. The climate in its range is mediterranean, with annual rainfall from . Nelson tentatively explains these disjunct populations in terms of natural climate fluctuations: during times of higher rainfall, the distribution of A. obovatus would have been much more extensive. Reductions in rainfall would cause the distribution to contract, but isolated populations could survive in favourable refugia. ==Ecology==

The western spinebill (Acanthorhynchus superciliosus) is the most frequent visitor to the flowers. A territorial species, the territories are smaller when they contain more Adenanthos obovatus bushes. Their long curved bills fit the tube-like flowers exactly, so that the pollen-presenter brushes against the spinebill's head while it is probing for nectar. The birds then carry pollen from plant to plant, fertilising other plants. A field study marking the pollen with fluorescent dye found that pollen could be deposited on flowers of plants up to away from the original flower visited. The New Holland honeyeater (Phylidonyris novaehollandiae) and brown honeyeater (Lichmera indistincta) have also been recorded with pollen from A. obovatus. The silvereye (Zosterops lateralis) drinks nectar from the flowers, but punctures the tube with its short bill. Larger honeyeaters in one field study tended to avoid A. obovatus, possibly seeking sources of more abundant nectar elsewhere. These species are too heavy for the fine branches and their bills are too large for the tubes. Adenanthos obovatus has been recorded as a source of nectar for the honey possum (Tarsipes rostratus) in winter and spring (early June to September), from field studies in the Scott National Park, replaced by A. meisneri in late spring and summer (late October to February). Adenanthos obovatus is highly susceptible to dieback caused by the water mould Phytophthora cinnamomi. Specimens in coastal dune vegetation were reported killed by the fungus Armillaria luteobubalina, with mycelial sheaths of the fungus beneath the bark of the root collar. ==Cultivation==

Described by Ken Newbey as "an outstanding ornamental species with average foliage and very attractive in flower", A. obovatus was first grown in Great Britain in 1824, and is the most commonly cultivated Adenanthos species in Australia. It flowers for most of the year, is an excellent attractor of honeyeaters, and grows in a range of climates. Propagation is by cuttings of the current season's growth, from which it strikes readily, ==Footnotes==