Lobelia purpurascens, in Family Campanulaceae is commonly known as Whiteroot.
It is native from Queensland to Victoria but is often a weed in lawns.
They are perennial prostrate, scrambling or erect herbs.
Prostrate stems can be over 30 cm long and the erect ones to or over 10 cm high.
The purple tinged stems are angular and prostrate ones may root at the nodes.
The main taproots are smooth, thick and white while other roots are short fibrous ones.
Stems usually have no hairs but there may be a few scattered ones.
Alternately arranged leaves may have a petiole 1 to 3 mms long but frequently have none.
There is a tiny bract on either side of the petiole base.
Blades, up to 3 cm long and 1.2 cm wide can be ovate, elliptic or lance-shaped.
The tip is pointed and there are typically 4 teeth on each side.
There are usually very small hairs on the upper surface near the edge.
The lower surface is usually purple or a paler green tinted with purple.
Axillary inflorescences are a solitary flower on a stalk (peduncle) up to 6 or 7 cm long.
The bases of the sepals are fused into a short tube with 5 spreading lobes.
The calyx tube is fused to the ovary wall and the corolla lobes and filaments insert on the top forming a hypanthium.
Sepal lobes are around 2 or 3 mm long with at least 1 pair of teeth near the base.
The resupinate (upside down) flowers have a corolla tube 5 to 10 mm long with 5 lobes.
The tube is slit almost to the base on the upper side and there are small hairs in the throat.
The two narrow pointed upper lobes (wings) are erect, 4 to 5 mm long and up to 1 mm wide.
The outer surface of the wings is usually the most coloured part of the corolla.
The 3 more spreading oblong lower lobes are around 7 mm long and 2 to 3 mm wide with a pointed tip.
Petals are white but often with a pink, blue or purplish tinge mainly on the outer surface.
Flowers are unisexual with male and female on different plants.
Male flowers have 5 stamens with filaments 4 to 5 mm long.
The anthers and top of the filaments are fused to form a tube.
Anthers open inwards through longitudinal slits.
Only some of the fused anthers, around 1.5 mm long have apical acute hairs.
The rudimentary ovary is around 3 mm long.
Female flowers have much smaller stamens with sterile anthers.
The staminode filaments have short hairs.
The inferior ovary, around 3 mm long has numerous ovules in the 2 locules.
The style holds a bilobed stigma.
The roughly spherical capsules, up to 1 cm long open into the 2 chambers
They have brown pitted seeds.
(Flowers I have seen all have a fleshy, slightly lobed yellow nectary on top of the ovary.
I have not seen this described for L. purpurascens but a similar nectary is present in other species such as Lobelia grayana, Lobelia monostachya and Lobelia niihauensis.)
J.F.
