Planchon 'Flora de Montpellier' 1864 page 20.) The horse-radish (Cochleria armoracia) spreads pertinaciously and is naturalised in various parts of Europe; though it bears flowers, these rarely produce capsules: Professor Caspary informs me that he has watched this plant since 1851, but has never seen its fruit; 65 per cent of its pollen-grains are bad. The common Ranunculus ficaria rarely bears seed in England, France, or Switzerland; but in 1863 I observed seeds on several plants growing near my house. (18/117. On the non-production of seeds in England see Mr. Crocker in 'Gardener's Weekly Magazine' 1852 page 70; Vaucher 'Hist. Phys. Plantes d'Europe' tome 1 page 33; Lecoq 'Geograph. Bot. d'Europe' tome 4 page 466; Dr. D. Clos in 'Annal. des Sc. Nat.' 3rd series Bot. tome 17 1852 page 129: this latter author refers to other analogous cases. See more especially on this plant and on other allied cases Prof. Caspary "Die Nuphar" 'Abhand. Naturw. Gesellsch. zu Halle' b. 11 1870 page 40, 78.) Other cases analogous with the foregoing could be given; for instance, some kinds of mosses and lichens have never been seen to fructify in France. Some of these endemic and naturalised plants are probably rendered sterile from excessive multiplication by buds, and their consequent incapacity to produce and nourish seed. But the sterility of others more probably depends on the peculiar conditions under which they live, as in the case of the ivy in the northern part of Europe, and of the trees in the swamps of the United States; yet these plants must be in some respects eminently well adapted for the stations which they occupy, for they hold their places against a host of competitors.]