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Yellow Oxytropis

Oxytropis campestris ssp. sordida

  • Name also: Yellow Milk-vetch, Field Locoweed (USA, Canada)
  • Family: Pea Family – Fabaceae (Leguminosae)
  • Growing form: Perennial herb. Taproot erect, strong, many-branched at top.
  • Height: 10–20 cm (4–8 in.). Stem woody at base, abundantly branched from base, Inflorescence stem leafless, hairy.
  • Flower: Corolla zygomorphic, yellowish white or occasionally bluish, approx. 15 mm (0.6 in.) long, Petals 5; the upstanding the ‘standard’, the lateral two the ‘wings’, the lower two united to form the ‘keel’, overall shape of corolla being butterfly-like, keel tapered, bluish violet, sharp-pointed. Calyx 5-lobed, black-haired. Stamens 10, filaments with fused bases. A single carpel. Inflorescence an axillary, long-stalked, dense, 5–15-flowered raceme.
  • Leaves: A rosette, stalked, stipulate. Blade pinnate, 8–15-pairs, with terminal leaflet. Leaflets tapered, with entire margins, hairy. Stipules united.
  • Fruit: 15–20 mm (0.6–0.8 in.) long, tapered, oval, black-haired, 2-parted, erect pod (legume).
  • Habitat: Esker woods, river banks, roadsides, rocky outcrops, fell heaths.
  • Flowering time: June–July.

In fact yellow oxytropis is the name of the more common subspecies campestris which has yellowish flowers. Better name for ssp. sordida which has more bluish flowers, would be Russian oxytropis or Eastern oxytropis but those names don’t exist yet. That is why the English name of this plant is yellow oxytropis (and field locoweed).

Yellow oxytropis’s strange-sounding name comes from its scientific name, which can be broken down into oxys, ‘sharp’ and tropis, ‘tip’, which refers to the corolla’s tapered, sharp-tipped keel. It has spread to Finland from the east, soon after the Ice Age some 10,000 years ago. The species apparently spread from two directions: from the Kuola peninsula and the Karelian Isthmus, and the plants still bear the legacy of this in their flowers. In the north the flowers are mainly blue, while in the south yellowish flowers are clearly in the majority, although there are of course always exceptions to the rule. The species usually grows on fells, but its oldest Finnish habitats are lateral moraines in the east of the country and sandy ridges. Yellow oxytropis favours steep, south-facing sunny ridges. Its current habitat is comprised of patches, which is probably a consequence of its formerly united habitat being fragmented. It seems unlikely that it has spread over large distances from one ridge to another because the large and heavy seeds that the plant holds up above the snow often land close to the mother plant. Difficulties in spreading have not prevented it being moved by people however to new habitats like road cuttings, banks and gravel pits.

Other species from the same genus
Other species from the same family

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