Myrsine australis

Myrsine australis is a small shrub or tree, growing from 3–6 metres tall with short upright branches that create a compact crown.[1][2][3] The trunk grows up to 20 cm in diameter, with the bark of the trunk and older branches a dark brown/black, whereas the juvenile branches are reddish, a distinguishing feature of this plant.[1][3] The leaves are coloured pale green with a yellow tinge on the top surface, while the underside of the leaf is a paler version of this.[1][3] Measuring 3–6 cm in length to 1.5-2.5 cm in width, the leaves are arranged alternatively on the stem and have a leathery texture.[1][2][3] The leaf margins are normally wavy, however some uncommon forms may also have flat leaf margins.[1][2][3] Each leaf blade is typically covered in round, translucent glands, and is connected to a red, approximately 5mm long, leaf stalk.[1] These leaf stalks, also called petioles, can vary in colour and size as a result of environmental conditions and local population trends.[4]

On average, Myrsine australis tends to flower between August and January, and produces fruit between September and December.[10] Its flowers are clustered on small stalks on the branchlets where older leaves have already been lost.[1] They are small and inconspicuous (like most other New Zealand native flowers), measuring from 1.5mm to 2.5mm in diameter, and are a cream to whitish colour, covered in small orange glands.[1][2][3] The flowers are unisexual, therefore some individuals produce only male flowers for pollen distribution, and other individuals produce only female flowers for fertilization and fruit growth.[1][2][3] The petals of the flowers are lanceolate, obtuse, free and revolute.[4] Due to the occurrence of flowering and fruiting periods overlapping, some specimens can display both fruit and flowers at the same time.[1] Red matipo’s fruits are drupes; a single seed is encased in a hard core, which is then covered in a fleshy outer layer.[1] The fruits measure 2-4mm in diameter, are coloured dark brown to black, and are commonly dispersed by kererū, tūī, tauhou, korimako, and blackbird, who eat the fruit, and dispose of the seed once digested.[1][2][3][11] The plant has the ability to retain a ‘Seed Bank’, with some seeds remaining dormant for a year or more and germinating at random intervals and amounts.[12] Seeds typically require a chilling period to enable germination to occur, and it is also suspected that after seed fall, embryos may still be developing.[11] Therefore, germination can take nearly four to five times as long in comparison to other New Zealand natives such as Hoheria angustifolia and Coprosma foetidissima which typically germinate far more rapidly.[12] These time periods are rough averages as each specimen of Myrsine australis has its own natural variety and irregular pattern.[11]

The genus Myrsine was first described by Linnaeus for Myrsine africana, a species with a broad native range in Africa, India and China.[3] This genus was originally split into three separate genera, Myrsine, Suttonia, and Rapanea, however due to a lack adequate characters to separate them, the around 300 species are now all combined under the one genus Myrsine.[1][2][3] Red matipo is a species that is often confused with another native New Zealand plant species, Pittosporum tenuifolium, common name Kōhūhū.[1] Although these two species are evolutionarily distinct, this confusion normally occurs when only the leaves are used for identification, as the bark of the young branches is distinctly red on red matipo, and black on Kōhūhū.[1] Both Maori and early Europeans utilised red matipo for its medicinal value, as its leaves, when boiled in water, provide a cure to toothache.[1] Scientific analysis of red matipo leaves today show it contains glucorinic acid, an arthritis treatment, and rutin, a treatment for blood vessel problems.[1] Many of the other Myrsine species are still today utilized for medicinal purposes, a particularly interesting example of this being M.africana, as it contains a substance called saponin which provides benefit to cancer patients.[1] Europeans also used red matipo wood for cabinet making when the milling of native forest was standard practice, however today, due to its hardy nature and appealing looks, it is more commonly used as a hedge plant.[1] Through plant breeding, horticulturalists have developed an even more visually appealing, variegated form .[1] Here, the center of the leaf is bright green/yellow, and is surrounded by a thin, inconsistent margin where the normal leaf colour is kept.[1]