Hakea laurina, the Pincushion Tree, is a Western Australian native from the protea family. Large, fragrant pincushion flowers hang like ornaments from evergreen branches winter and spring. Prunes into an attractive large shrub for acid soils. Prefers poor, gravelly soils and full sun. Good on the coast.
Halimium, the Great Sunrose, is an evergreen shrub to 120cm for well drained, alkaline soils. In spring and summer large, bright yellow, single rose-like flowers smother the plant. Very drought hardy but a little frost tender.
Hardenbergia, the Sarsaparilla, is an Australian groundcover which is often grown as a tidy climber. The dainty purple, pink or white flowers resemble miniature wistaria and provide welcome winter colour. Evergreen foliage makes this vine attractive all year. Easily grown in most well drained soils in sun or part shade. Avoid heavy commercial feeding!
If you want the same effect on a smaller shrub try Hovea which will reward with masses of flowers on every branch even in the dappled dry shade found under trees.
Hebe is also known as Veronica or New zealand Lilac. There are at least 80 species and many more hybrid forms from big shrubs to creeping groundcovers. They are nearly maintenance free, hardy in most soils and on the coast and are highly ornamental in both leaf and flower. Prune back by one half in early spring and feed around the root system at the same time. Be sure the site is very well drained. This worthwhile shrub is named after the Greek goddess of youth.
Heliotropium, commonly called Cherry Pie for it's distinctive, fruity fragrance is a cottage garden classic suitable for sun or dry part shade if the soil is moderately rich and the air is humid. Cut back hard in early spring.
Hibbertia, the Golden Guinea Flower, comes in 70 species. The best known of these showy Australian natives is H. scandens, a lovely evergreen climber adorned with buttercup yellow flowers over a long period. Sandy soils or dunes give best results.
They are often confused with the 400 species of Hypericum, the St. John's Wort, which also have showy, yellow, buttercup flowers on wiry, evergreen bushes. They thrive in full sun to part shade in almost any soil. Many varieties also have very attractive berries and prune easily into attractive hedges.
Homeria is a little known Australian cormous iris with long, thin leaves topped with yellow, salmon or apricot flowers that resemble freesia or montbretia and are fragrant. Hardy!
Also seldom seen but worth tracking down is Hypoxis, the Star Grass, another hardy bulb for acid, well drained soils in sunny spots. Brilliant, star-like amaryllis flowers in yellow, lilac or white arise above hairy, thin foliage.
For something really stunning in the subtropical dry garden try Hylocereus, the Princess of the Night or Night Blooming Cereus. 30cm long buds open to 23cm white blooms with a remarkable perfume. This epiphytic succulent cactus climbs in dry, sandy part shade to 8m. and flowers at night or indoors!