Electronic Flora of South Australia
Electronic Flora of South Australia
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Electronic Flora of South Australia species Fact Sheet

Family: Fabaceae
Swainsona laxa

Citation: R. Br. in Sturt, Exped. Centr. Aust., Bot.App. 18 (1849) var. laxa.

Synonymy: Swainsona laxa, Swainsona rigida

Common name: Yellow swainson-pea, yellow Darling pea.

Shrub-like herb, completely glabrous except for a few hairs on the youngest parts, glabrescent later; stems erect or ascending, 15-50 cm long, finely striate; leaves 4-17 cm long, with 11-19 leaflets; leaflets obovate or narrow-obovate, 8-27 x 5-15 mm, emarginate, rarely obtuse, glabrous; stipules ovate, acute, 5-15 mm long, with an obliquely decurrent base, broad and leafy.

Flowers 9-11 mm long, yellow, in 12-20-flowered racemes, on peduncles 12 to over 20 cm, elongating in fruit, usually occupying the distal two-thirds of its length; pedicels 2-4 mm long, exceeding by about half the narrow deltoid scarious bract; bracteoles at the base of the calyx, filiform, 0.5-1 mm long; calyx 3-4.5 mm long, contracted into a conical base; teeth triangular, shorter than the tube, glabrous inside and out; standard orbicular, notched, parallel-nerved, without calli, on a rather slender 1.5-2.5 mm long claw; wings shortest, oblong-lanceolate, gently geniculate, auricle big, orbicular, above a slender 1-2 mm long claw; keel about as long as the wings, semicircular, obtuse, shortly auriculate above a short claw; ovary stipitate, fusiform, flattened, to 20-ovulate; style tapering into a slender tip, evenly recurved, scantly bearded all along, few more hairs at the tip and a tuft of hairs behind the straight stigma.

Pod distinctly stipitate, elliptic to lunate, 10-25 x 8-15 ram, much inflated, with thin-papery walls but flattened, suture ridged and not impressed, reticulate, reddish or not, to 10-seeded; seed cordate, c. 2 x c. 1.8 mm, slightly compressed, dark-brown to blackish, pitted.

Distribution:  S.Aust.: LE, EP.   Vic.

Conservation status: native

Flowering time: probably all the year round, depending on rainfall.

SA Distribution Map based
on current data relating to
specimens held in the
State Herbarium of South Australia

Biology: No text

Taxonomic notes: Shows similarities with S. colutoides which is a more robust plant having distinct hairs on the inner side of the calyx as well as 2 callosities on the standard and the pod is 25-50 mm long although similar in shape.

Author: Not yet available

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