Phyllanthus.
Family Phyllanthaceae > Subfamily Phyllanthoideae > Tribe Phyllantheae.
Phyllanthus is the largest genus in the family but the number of species is uncertain.
Estimates range from 600 to over 1200 with Plants of the World Online (Kew) accepting 858.
The problem is caused by genera such as Breynia, Glochidion, Phyllanthus, Reverchonia and Sauropus being so similar.
Which of these are included in Phyllanthus determines the number of species.
There are around 60 native and naturalised species in Australia with around 11 in S. E. Queensland.
The following is a brief and simplified description of a complex genus.
There are trees up to 25 m high, dense shrubs to 3 m, herbs 15 to 50 cm high, prostrate forms only 3 cm high, climbers
and a few succulents and plants growing in water.
Small branches can be round, angular, elliptic or flat in cross section and smooth or ribbed.
Some plants have regular branching patterns all with similar leaves in spirals or 2 ranks.
Many species have 2 to 4 different types of branches (phyllanthoid branching) with long erect
main stems and short stiff side branches having different leaf types.
The are 3 main types of stems are:
1) The main, usually erect branches which continue to grow have leaves reduced to scales (cataphylls).
2) Short-shoots with very close scale-like leaves.
3) Lateral (horizontal) shoots of limited growth with normal foliage leaves often in one plane (distichous)
so the shoot looks like a pinnate leaf. Some of these branches will carry the flowers.
The alternately arranged leaves are of 2 types – scale-like and normal foliage.
Both have cream, red, red-brown to black stipules at the base with those under the scale-like leaves on the erect main stem being
larger than those under the foliage leaves.
The scale-like leaves on the erect main stem (cataphylls) do almost no photosynthesis.
Normal foliage leaves, often in 2 ranks are evergreen or deciduous.
Sometimes on a petiole up to 2 mm long they have a stipule at the base.
The linear, elliptic or oblong blades, 3 mm to 7.5 cm long have a pointed or rounded tip often with a short abrupt point (mucro).
The blade can be flat or the edges may roll upwards or back.
Blades may be smooth or have a few to dense, long or short mostly simple hairs.
Axillary inflorescences are a solitary flower or a variously arranged cluster with some up to 12 cm long.
Flowers are almost always unisexual with most species having both on the same plant (Australia has one bisexual species).
They are on the mainly short horizontal side branches with normal leaves.
Male inflorescences are typically 2 flowers, or 2 pairs in the lower leaf axils but there may be up to 10.
Females are typically a solitary flower in the upper leaf axils but some species have 2 female or 1 female with up to 3 males.
All are typically tiny pendant flowers a few mms wide on a thin peduncle up around 1 cm long.
They have 4 to 6 sepals up to around 5 mm long, usually in 2 whorls with their bases free or fused.
There are no petals but the red, pink, white, yellow or green sepals may be petal-like.
Both sexes have nectaries – in males there are usually to 4 to 6 lobes and in females an annular disc sometimes with teeth or lobes.
Male flowers.
There are 3 to 6 (2 to 15) stamens with filaments that are free, partly or fully fused.
Basifixed anthers open outwards or sideways mostly through longitudinal or horizontal slits.
There is no rudimentary ovary.
Female flowers.
The superior ovary has 3 (4 to 12) locules each with 2 ovules.
The 3 (4 to 12) styles may be free and spreading to erect and basally fused into a column.
Each stigma has 2 lobes or 2 branches that are erect to curved back.
There are no staminodes.
Fruit are almost always dry slightly flattened spherical capsules 1.5 to 8 mm across.
They typically have 3 chambers and split open at the septum between the chambers or into the chamber (septicidal or loculicidal).
The 6 seeds have a 3-angled inner surface and a rounded outer.
The thin covering may be smooth, finely nodular or ridged.
Rarely are the fruit fleshy and drupe or berry-like.
J.F.
