The genus Araucaria contains some of the most distinctive trees in existence, including the widely grown A. araucana, the Monkey-puzzle, and A. heterophylla, the Norfolk Island Pine, whose whorled branches are so familiar a sight in tropical gardens. There are 19 species in the genus, with a scattered distribution in former Gondwanaland (although they occurred in Laurasia as well). Two are from South America, while the others are from a cluster of localities in Australasia centred on New Caledonia, where an astonishing 13 species occur – 12 as endemics. All 19 species are substantial trees, with a stout, straight and usually unbranched main trunk bearing similarly stout, spreading branches borne in whorls. The bark is resinous. In youth the branches occur from the base, but in maturity the lower branches usually senesce, leaving the tree with an often ragged-looking crown. The branches are clad along their length with stiff evergreen scale leaves, varying from small and needle-like to broad and rigid, usually sharp-tipped. Buds are indistinct among the foliage. The trees are usually dioecious, but hermaphrodites sometimes occur, and are self-fertile. Male strobili are solitary or clustered, forming dense cylindrical ‘cones’ borne upright from the branches. Female cones are large and globose, formed of many scales which fall apart at maturity, persisting for two to three years on the tree. Each scale has one (usually winged) seed adherent to it. (Dallimore & Jackson 1966; Krüssmann 1985b; Farjon 2001).
The Monkey-puzzle Araucaria araucana – so beloved of the Victorians, and still commonly planted – is generally appreciated and reviled in about equal measure. It must be said that a solitary scrawny specimen in a suburban setting is not an inspiring sight, but a well-grown young one is a handsome object and with thoughtful modern planting around it, need not appear so out of place as it often does. It is the regular branching that makes the tropical and subtropical species of Araucaria so attractive when young, and gives the impetus to attempts to grow them in our area. In addition to the species described below, A. cunninghamii D. Don from Australia (Queensland) and New Guinea may be worth attempting in mild coastal gardens, having reached 18 m at Penjerrick, Cornwall in the much cooler past (1928 record, The Tree Register 2018). A. hunsteinii K. Schum. from New Guinea is in cultivation at Tregrehan, where a young tree is growing steadily. Although Krüssmann (1985b) describes several other tropical species, there is no evidence that these have ever been cultivated outdoors in our area, and they are omitted from our cross-references. Propagation is by seed.