156 Dr. H. Franklin Parsons on the Habits tk., of Plants. 



upon the growth of the individual plant, rather than to the 

 modification of the species by natural selection; for plants 

 which are dwarf and fleshy when growing on the sea- coast, e.g., 

 Glaux maritima, Plantago maritima, and Aster Tripolium, are 

 rank and weedy in habit when growing near the upper parts of 

 estuaries, where the tidal water which reaches them is only 

 slightly brackish. The presence of a large proportion of salt 

 in the sap would promote endosmosis and impede evaporation, 

 and thus tend to produce a swollen state of the leaf. 



10, Another distinct habit of growth is that of bulbous-rooted 

 plants. In the British flora true bulbs are hardly met with, 

 except in the orders Liliaceae, AmaryllidacesB, and IridaceaB, 

 though an approach to a bulb is met with in some other plants, 

 as Ranunculus bulbosus and Phu/uicula vulgaris. Bulbous and 

 cormous-rooted plants commonly flower in the spring and have 

 linear root-leaves and a leafless flowering stem or scape. The 

 leaves commonly follow the flowers, or, if they appear at the same 

 time, persist after them ; and they store up in the bulb a supply 

 of nourishment from which the next year's flowers are produced. 

 Sometimes, however, as in Ornithogahm pyrenaicum, the leaves 

 precede tbe flowers, and are withered by the time that the latter 

 appear. The size of the bulb seems to depend a good deal on 

 the breadth of the leaves : thus the Crimean snowdrop [Galanthus 

 plicatiis), and the Siberian squill, which have broad leaves, have 

 much larger bulbs than the common snowdrop and the Scilla 

 bifolia. A few bulbous and cormous-rooted plants flower in the 

 autumn, e.g., several species of crocus, the meadow saffron 

 (Colchicum autumnale), and the garden-plants Amaryllis lutea and 

 Zephyranthes Candida. All these, though belonging to different 

 orders, have crocus-like flowers ; and the Colchicum resembles 

 some of the true autumn-flowering crocuses in that its leaves 

 and seed-vessels are not produced until the following spring. 



11. Instances of superficial resemblances to species not nearly 

 related rather than to those more nearly akin may be met with 

 among the cryptogamic orders of plants. Thus in several dis- 

 tinct genera we find ferns with feather-shaped fronds or leaf- 

 organs like those of the male fern. Polypodium alpestre so 

 closely resembles the lady-fern [Athyrium filix-fcemina), that in 

 the absence of fructification it is all but impossibe to distinguish 

 the two. Again, Polypodium Vryopteris and Robertianum, and 

 Cystopteris montana, in their long creeping rhizomes and hori- 

 zontally spreading fronds borne on long stalks, closely resemble 

 in miniature the common brake-fern. 



In several genera of fungi, as Dadalea, Polyporus, Hydnum, 

 Auricularia, Stereum, &c., we find species of a leathery or corky 

 texture growing attached by the side to trees or decaying wood, 

 and so closely resembling one another that until the under side 



