Atkinsonia
| Atkinsonia | |
|---|---|
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Core eudicots |
| Order: | Santalales |
| Family: | Loranthaceae |
| Genus: |
Atkinsonia F.Muell. |
| Species: | A. ligustrina |
| Binomial name | |
|
Atkinsonia ligustrina (Lindl.) F.Muell. |
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| Synonyms | |
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Atkinsonia is a parasitic shrub with oppositely set, entire leaves and yellowish, later rusty-red colored flowers, that is found in Australia. It is a monotypic genus, the only species being A. ligustrina, and is assigned to the showy mistletoe family. It is sometimes called Louisa's mistletoe.
Atkinsonia ligustrina is a stout upright evergreen shrub of 1-2 m high, that parasitises on the roots of other woody plants, but photosynthesises for itself. It has twenty four chromosomes (2n=24).
The primary roots are long-lived, fleshy, bear many scars, and turn blue when damaged. Secondary roots bearing the taproots (or haustoria) are short-lived and devoid of root hairs.
There are numerous red–brown branches that split into smooth branchlets that break easily.
The leaves are oppositely set along the branches, but sometimes apparently randomly positioned if some leaves have fallen, are slightly fleshy, spread out, initially bright green and later somewhat more dull green 2–5 cm long, ½–1 cm wide, the downward facing surface felty, an entire margin that has a identical curve from the tapering foot, that ends in an approximately 2 mm long leaf stalk, and a blunt tip at the other side.
The up to eight sweetly scented flowers in each inflorescence are set in racemes in the axils of the leaves, and are almost the same length as the leaves themselves, and appear in November. Each flower has a short stalk, and is subtended by a pair of bracteoles close to the flower, and a third bract further down. The mostly six (sometimes up to eight) petals are spreading narrow strips of approximately 7 mm long, yellow in color, later becoming more rusty red. The anthers are short, pale yellow, and are merged to the petal at the foot.
The drupe-like oval to egg-shaped fruit of about 1½ cm long, is initially green, but develops a red skin when ripe in about March. It hides a thin sticky layer around the seed. They are eaten or shed before the following season's flowerbuds occur.
Allan Cunningham discovered this species in 1817 and called it Nuytsia ligustrina. This name was published by Lindley in 1839, but not accompanied by the required description. Ferdinand von Mueller described the plant in 1861, thus finally providing the plant with a name. When he was able to see the fruits, he decided the species should be in a new genus, Atkinsonia, and he made the new combination Atkinsonia ligustrina in 1865. Later, in 1883, G. Bentham and J.D. Hooker assigned A. ligustrina to Loranthus, but since Loranthus ligustrina (now Helixanthera ligustrina) had already been used by Nathaniel Wallich in 1824 for another species from India, a new combination, Loranthus atkinsonae, was created. Adolf Engler first included our species in Gaiadendron in 1894, to subsequently distinguish the subgenera Atkinsonia and Eugaiadendron in 1897 based on the morphology of the inflorescences, and eventually in cooperation with Ernst Hans Ludwig Krause restoring both genera to their original circumscription in 1939.
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