Plant Highlight: Banksia heliantha
(This plant was formerly known as Dryandra quercifolia.)
About the genus
Banksia is a genus in the Proteaceae (the Protea Family), and most of them are shrubs, though some of the larger ones are trees. Almost all are Native to Australia (one extends northward to nearby islands), with the greatest concentration being found in Western Australia. As defined today, Banksia contains about 170 species, having been much enlarged in 2007, when all of the species in the related genus Dryandra were merged into it. In general, plants named as Dryandra have dome-like flower heads, contrasting with the more cylindrical flower heads seen with most of the other Banksia species, but genetic evidence showed that the ancestry of the two is intertwined, so they were united into Banksia, this being the older name. One of the species whose name got changed is Dryandra quercifolia; because there was already a Banksia quercifolia, it was necessary to coin a new species name, and B. heliantha was the name selected.
About the plant
As is true of most of the Banksia species, Banksia heliantha has a shrubby evergreen growth habit, and it may attain a height of up to 6½ feet (2 m). Its stiff leaves are 2 inches to 3½ inches long (5 to 9 cm) and .9 inch to 2 inches wide (2.2 to 5 cm), a little wider above the middle than below. They have a prickly appearance because of the sharp-pointed teeth along the margins, with the points either projecting out at right angles or else bending forward toward the leaf tip. The old name Dryandra quercifolia refers to the resemblance of the leaves to those of prickly-leaved oaks (Quercus is the genus to which the oaks belong). The upper leaf surface is glossy deep green, while the underside is a little paler because it is peppered with tiny white tubercles. The petiole, or leaf stalk, is .3 to .4 inch long (8 to 10 mm). When leaves first emerge they have a coppery color, but they soon change to green.
About the flowers and fruits
In habitat, the main flowering period for Banksia heliantha is in late winter to early spring, but our plants at the Ruth Bancroft Garden in California generally flower earlier than this, in late fall to winter. The flowers are clustered in dense heads, with their appearance changing dramatically through the flowering cycle, while managing to look elegant at each stage. Initially, the flowers are enclosed by the numerous narrow dark brown wooly-edged bracts that encirle them. As the numerous small flowers expand and open, the flower head changes to a rounded yellow cone cupped by the dark bracts, and then finally to a sea of yellow stigmas as the flowers mature; the elongated stigma of each flower is its most conspicuous part. Only a minority of the 140 to 160 flowers in the cluster ever get successfully pollinated and go on to form the egg-shaped hairy follicles that hold the seeds.
Care and maintenance
Banksia heliantha prefers non-alkaline good-draining soils, and sun for at least part of the day. It comes from Australia’s Mediterranean-climate region, and it does not do well in places with humid summers. Its native area of occurrence is near the southern coast of Western Australia.
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