From the root stock arise one or more prostrate branches which creep over the rocks and soil, and turn upward at their extremities to terminate in a bunch of the brightly-coloured flowers. The grey-green leaves are narrow and succulent, and are arranged in whorls of four on the stem. The flowers are furnished with a long spur which contains the honey, and are only visited by bees and humble-bees. The common humble-bee has a long enough tongue to reach to the tip of the spur and is the chief agent in the fertilisation of the plant. The orange-yellow spot at the only opening to the flower is equivalent to a notice “this way to the honey.” Should no insect visit a flower self-fertilisation will nevertheless occur and seeds will be produced all the same. A variety of this plant, with flowers of a uniform red-violet colour and without any orange-yellow spot, grows on primary granitic rock. A second and much rarer type has pure yellow blossoms.
The plant is sure to be easily recognised. The prostrate stem, narrow leaves, and entirely closed up flowers that grow together in bunches are some of the more characteristic features.
Plate XXXII.
LINARIA ALPINA. MILL.
The Alpine Toad-flax. Linaire des Alpes. Alpen-Leinkraut.
The Alpine Balsam
(ERINUS ALPINUS)
The Alpine Balsam is a characteristic rock plant of the limestone Alps. Taking root in the clefts of the rocks, it sends out radiating branches in all directions, which adhere closely to the surface. It may also be sought in dry mountain meadows and among the grass of dry stony slopes, and is fairly common between 4000 and 7000 feet. Sometimes it is met with at a lower altitude in rocky places. The leaves, which are broader at their free extremities and covered by short hairs, are crowded together at the base of the stem. They have deeply serrated edges. The violet-purple or occasionally white flowers, which are formed of five petals united at their bases, are borne at the extremities of the branches. The Alpine Balsam is found not only in the Swiss Alps but also in the Tyrol, the Jura, the Vosges and Pyrenees. It flowers from early June till August.
The flowers of the Bird’s-eye or Mealy Primrose (Primula farinosa) are not unlike those of the Alpine Balsam, at any rate at first sight. But each Mealy Primrose plant bears but a single leafless flower-stem which terminates in a cluster of flowers. Moreover, the Mealy Primrose is found in moist meadows and boggy places, and rarely among rocks, and its leaves have a grey, powdery bloom on their lower surfaces.