6. Plumed, lophospores. In the fruits of this class, the style is the part usually modified into a long plumose organ, possessing a high degree of mobility, as in Pulsatilla, Sieversia, and Clematis.
7. Awned, ascospores. These are almost exclusively grasses, in which the awns serve for distribution by wind, water, or animals, and even, according to Kerner, by hygroscopic creeping movements. The mobility in many cases is great.
8. Spiny, centrospores. This group contains a few representatives which possess a moderate degree of mobility by attachment, as in Tribulus and Cenchrus.
9. Hooked, oncospores. The members of this group are extremely numerous, and the degree of mobility as a rule is very high. All exhibit in common the development of hooks or barbs, by which they are disseminated in consequence of attachment, though the number, size, and disposition of the hooks vary exceedingly.
10. Viscid, gloeospores. In these, the inflorescence is more or less covered with a viscid substance, as in species of Silene, or the fruit is beset with glandular hairs, as in Cerastium, Salvia, etc.
11. Fleshy, sarcospores. These are intended for dissemination by deglutition, largely by birds; the effectiveness of the modification depends in a large degree upon the resistance of the seed envelope to digestion. The mobility varies greatly, but the area over which migration may be effected is large.
12. Nut-fruited, creatospores. This group includes those plants with nut fruits which are carried away and secreted by animals for food.
13. Flagellate, mastigospores. These are plants with ciliate or flagellate propagative cells, i. e., zoogonidia, as in Protococcus, Ulothrix, Oedogonium, Ectocarpus, etc., or with plant bodies similarly motile, Bacteriaceae and Volvocaceae.
265. Position of disseminule. The position on the plant of the organ to be disseminated, i. e., its exposure to the distributing agent, plays a considerable part in determining the degree of mobility. In the majority of plants, the position of the inflorescence itself results in maximum exposure, but in a large number of forms special modifications have been developed for placing the spores or seeds in a more favorable position. In both cases, there are often present also devices for bringing about the abscission of the seed or fruit. It is, moreover, self-evident that the height of the inflorescence above ground or above the surrounding vegetation is likewise of considerable importance in increasing the trajectory. It is yet too early to make a complete classification of contrivances for placing disseminules in the most favorable exposure, but the following will serve as a basis for future arrangements.
1. In all operculate Discomycetes, and especially in the Ascobolaceae, where the asci project above the hymenium, the spores are raised above the surface by tensions within the apothecium. This might be regarded as dissemination by expulsion, if it were not for the fact that the spores fall back into the cup, unless carried away by the wind.