The White Dryas, or Silver-herb as the Swiss call it, is a characteristic Alpine plant which is found all over Switzerland between 3000 and 8000 feet, and even descends to the plains with some of the rivers. It is common in dry mountain pastures and rocky places, and seems to grow best on limestone soil. Often the bare surfaces of rocks and boulders are thickly covered with its matted growth, which persists from year to year as soil gradually accumulates around it.
The thick dense rootstock gives rise to long trailing branches, which extend in all directions and bear the leaves and flowers. Associated with the root tips is a curious fungus growth, which from its constant presence is thought to be of value to the plant. The tough leathery evergreen leaves have rolled back notched edges. Their upper surfaces are dark green, smooth, and polished, and devoid of the stomata or little pores by which air is absorbed by green plants generally; the lower surfaces are covered by thick white felt-like hairs. The flowers, which appear from May till July, resemble those of the Alpine Anemone, but are smaller. They have usually eight petals, hence the Latin name. Inside the petals are a large number of stamens arranged in the form of a ring, and inside these again a honey secreting gland which surrounds the mass of closely packed carpels in the centre of the flower. The carpels bear long silky styles, which grow out into beautiful feathery appendages as the seeds ripen—another point of resemblance to the Alpine Anemone. The carpels become ready for pollination before the stamens shed their pollen. Then the outermost stamens open, and only after several days have elapsed do the innermost stamens become mature. A little consideration will show how wonderfully this arrangement is adapted to favour the cross-fertilisation of the carpels by pollen brought from another flower by the agency of insect visitors. Should this, for any reason, fail, self-fertilisation will almost certainly be effected by means of the pollen from the innermost stamens. If a large number of plants of the White Dryas be carefully examined some will be found with flowers containing both stamens and carpels, as above described, while others, less numerous, have flowers with stamens only. These will of course produce no seeds. Some plants, again, will be seen to bear both kind of flowers. The White Dryas is found in the mountainous districts of Europe and in the Arctic regions of the new and old worlds. The plant will be readily recognised, for its leaves are quite different from those of an anemone.
Plate XV.
DRYAS OCTOPETALA. L.
The White Dryas or Silver-herb. Dryade à huit pétales. Echte Silberwurz.
The Alpine Rose
(ROSA ALPINA)
THE Alpine Rose or Dog-Rose must not be confounded with the Alpenrose. The resemblance is only in the names, for the Alpenrose so much beloved by the Swiss is really a rhododendron and quite a different plant. The Alpine Rose is a shrub sometimes 8 or 10 feet high, and only a single branch is shown in the photograph. It is found on the borders of mountain woods and in bushy places, from the lower slopes up to about 7000 feet, and flowers in May, June, and July. The leaves consist of seven to eleven leaflets, and there are broad stipules at the base of each leaf. The sweet-scented flowers are of a rich rose-red colour. The sepals are exceptionally long and project beyond the petals; this is especially noticeable in the bud. The fruit or hip is flask-shaped and rather narrowed at the base. Thorns are as a rule absent from the flowering branches, but are generally to be found on the lower and younger shoots, which point downwards. Sometimes they are absent altogether. The Alpine Rose is found pretty abundantly in the mountain woods of Southern and Central Europe, but does not extend to the North. Thus it grows in the Pyrenees, Auvergne, the Balkans, and in one part of the Black Forest.
The Dog-Roses are phenomenally difficult to distinguish from one another, and as many as fifty Swiss species are described. The characteristics above mentioned, and especially the high elevation at which it is found, will assist in the recognition of the present species. By the arrangement and character of the leaves and spines and the shape of the fruit, the Alpine Rose itself has been sub-divided into some thirty sub-species.