Plate XXXIII.
ERINUS ALPINUS. L.
The Alpine Balsam. Erine des Alpes. Alpen-Leberbalsam.
The Leafy Lousewort
(PEDICULARIS FOLIOSA)
The Louseworts as a whole have been exceedingly successful in the Alps. No less than fourteen different species are to be found, and some of them are exceedingly common. In spite of their unpleasant name they are for the most part really beautiful plants, and as a group they are interesting in several ways. In the first place, they are all in some degree parasites on other plants. Branches arise from the roots which attach themselves to the roots of neighbouring plants and absorb from them water or salts or even organic nourishment. The Leafy Lousewort is not a great offender in this respect, but other species are capable of completely destroying many of the surrounding plants. The method of pollination of the Lousewort flowers is also somewhat remarkable. The flowers are only visited by humble bees, for no other insect appears to be strong enough to force an entrance into the flower. As may be made out from the photograph, the flower consists of two lips. In the upper is a vertical slit through which the stigma alone projects, but immediately behind the slit are the four stamens. The lower lip forms practically a landing stage for insect visitors. When the humble-bee alights on the flower his head is sure to come in contact with the projecting stigma and some of the pollen which he unconsciously carries with him will be removed. As he bends forward and thrusts his head into the flower to suck the honey the vertical slit in the upper lip will be widened out and the stamens will protrude and strike the insect’s head. When the humble-bee at last leaves the flower to continue his journey its various parts will resume their former relative positions. Should no insects visit the flower self-pollination will occur. This appears to be the usual course of events in the North where humble-bees are scarce. In Spitzbergen, where there are no humble-bees, a nearly-related species, Pedicularis lanata, is said to be regularly self-fertilised without apparently suffering in any possible way.
The Leafy Lousewort here illustrated is the commonest variety in most districts. It is a tall, stately plant, often some two feet high, which is found on grassy slopes and in rocky places between 3500 and 7000 feet, and grows best on a limestone soil. The large fine-divided leaves are even found among the pale yellow flowers on the flower-stem. The plant flowers in June and July, and is found in the Alps, Pyrenees, Vosges, and Jura. It will be readily recognised by its alternate leaves, and pale yellow hairy flowers, without any beak-like projection at their summits. Pedicularis Oederi, which is a little like it, has no foliage leaves between the flowers, which are devoid of hairs, and have a blackish red spot on either side of the upper lip.
Plate XXXIV.