Desmodium scorpiurus  (Sw.) Poir. 1819

pronounced: dez-MOH-dee-um skor-pee-YUR-uss

(Fabaceae – the pea family )

subfamily: Faboideae – the bean sub-family

common names:  Scorpion Tick Trefoil, Tick Trefoil

Desmodium leaf Desmodium scorpiurusscorpion tick trefoil is derived from the Greek δεσμος (desmos), a band, referring to the joined pods; scorpiurus is from σκορπιος (skorpios), a scorpion, and ουρα (oura), a tail, referring to the shape of the pods.

This is a creeping herb, with hooked hairs and tiny flowers. It generally creeps over other plants to about 60 cm in height, using the hooked hairs as a climbing aid. The plant photographed was straggling over the Ixora and Yedda hawthorn hedge outside the site of the former Magnetic Island Service Station in Granite Street, Picnic Bay, together with a tangle of Siratro. If the plant finds nothing to creep over, it is procumbent.

flowering 1 flowering 2This vigorous, widely adaptable legume is a native of tropical America, the West Indies, and south to Peru. It was introduced as a pasture component into Taiwan, Australia, New Guinea, the Philippines and some of the Pacific islands. It is widely naturalized in Australia across the top end, and is found among medium trees, in sand or loam, occupying river levees, behind coastal dunes, and growing in cropland, especially when it is irrigated. The plant spreads quickly, because its sticky, hairy pods adhere to animals and clothing.

The leaves are trifoliate, alternate, spiral, stipulate, petiolate, with the petiole 20–40 mm long; the leaflet blade is 25–43 mm long, 12–30 mm wide, elliptic, the base rounded, the margins entire, the apex obtuse or retuse; the blade is hairy.

flower 1 flower 2The flowers (July to October) are in racemes; they are predominantly white or pink or purple, very irregular, pedicellate, the pedicel 50–7 mm long, the perianth 2-whorled; the calyx is 2–3 mm long, with 5 sepals, all the sepals joined. The corolla is to 4 mm long, with 5 petals, some petals joined. There are 10 stamens, free of the perianth, both opposite and alternating with the corolla parts, coherent to each other (9 fused, 1 free).

seed pods developing mature seed podsThe plant is lomentaceous, the loments pale brown, of about 6 articles, and with hooked hairs, non-fleshy, 3–4 cm long, 1.5–2 mm wide. The segments are approximately twice as long as they are broad.

Desmodium scorpiurus differs from Desmodium tortuosum in having shorter stipules and narrower loments.

In pasture, the Scorpion Tick Trefoil forms a good mixture with short grasses such as Paspalum and with other legumes. It stands treading and is very palatable until it dries out, and has a protein content of about 19%.

Photographs taken Picnic Bay 2011, 2016, Geoffrey Bay 2016

Page last updated 30th December 2017







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