There are 400 to 450 species with 5 either native to, or naturalised in, Australia.
Shrubs, some trees and annual or perennial herbs.
The branches and leaves can have mixes of simple, stellate and glandular hairs.
The alternate leaves can be in a spiral or 2 ranks.
There are small stipules at the base of the (sometimes very short) petioles.
The simple, ovate blades are large to small and soft or leathery.
The margins often have blunt or sharp teeth.
Some have various types of hairs and glands.
The separate male and female flowers are usually on the same plant.
Terminal and/or axillary inflorescences are branched or unbranched spikes.
In each position they can be solitary, or paired male and female spikes.
Alternately each inflorescence can have male and/or female flowers.
When mixed the female flowers can be at the top, centre or bottom of the spike.
Male inflorescences are often catkins – small, dense clusters of flowers on a spike.
Each cluster or glomerulus has small, inconspicuous bracts under it.
The small flowers, on short stalks, have 4 sepals and no petals.
There are usually 8 (16) free stamens on a raised receptacle.
The wide stamen filaments hold oblong or linear, basifixed anthers opening via long slits.
Female inflorescences can be a solitary flower or groups of 3 (5) in a leafy bract.
The leaf-like, toothed or lobed bracts continue to grow.
Some species have inconspicuous or no bracts.
The small flowers, on almost no stalks, have 3 (4 – 5) sepals and no petals.
The superior ovary has 2 or 3, mostly fused, carpels each with 1 ovule.
The 2 or 3 styles can be free or partly joined.
Each may be simple or branched a number of times so the number of stigmas varies.
The fruit are small, 3 (2) lobed capsules that split between the segments – septicidal.
Each segment then splits to eject its single small seed.