Lathyrus latifolius.
The Perennial or Broad-leaved Sweet Pea is naturalised in scattered areas of S.E. Queensland.
It is a minor weed but occasionally seen in gardens.
With no support plants can sprawl over large areas but with support they are up to 2 or 3 m high.
The angled stems have wide green wings.
Plants have no hairs.
Alternate leaves, in a spiral are on a winged petiole up to 5 cm long.
There is a green leafy stipule, up to 3 mm long on either side of the petiole base.
The persistent ovate to lance-shaped stipules may have small pointed basal lobes.
The pinnate leaves have a winged midrib with 1 pair of leaflets and a branched terminal tendril.
The ovate to elliptic leaflets can be up to 8 cm long and 3 cm wide.
The blue-green leaflets have a wedge-shaped base and a pointed tip with a mucro (small abrupt point).
Axillary inflorescences are on a stalk (peduncle) up to 20 or 25 cm long.
This holds the flowers above the leaves especially on prostrate plants.
The thread-like bracts are a few mms long and may fall early.
Occasionally a single flower but usually there are up to 10 or 15 spread out along the midrib.
Flowers, 2 to 3 cm long and wide are on a stalk or pedicel up to 2 cm long.
The calyx, up to 1 cm long has a bell-shaped base with 5 teeth.
The teeth vary from equal in length to shorter than the tube.
The 5 petals form a typical pea-like flower with a wide standard.
The 2 wing petals may be free or joined to the keel.
The dark purple, pink, rose or purplish-pink petals fade to white.
(There are cultivars with white, pale and deep pink flowers.)
The stamens are in 2 sections with most forming a tube open at the top.
The ovary, sometimes on a stalk has 1 locule with a varying number of ovules.
The single style has hairs on the upper surface and a small head-like stigma.
The smooth seed pods are 5 to 10 cm long and 1 cm wide.
The upper groove (suture) may have a narrow wing down either side of it.
Pods mature from green to brown and split to throw the seeds out.
The up to 15 seeds have a network of raised ridges on the surface.
J.F.
