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These differences have been attributed by some authors to pressure, and the shape of the seeds in the ray-florets in some Compositae countenances this idea; but, in the case of the corolla of the Umbelliferae, it is by no means, as Dr. Hooker informs me, in species with the densest heads that the inner and outer flowers most frequently differ.
Much snow lay on the ground in patches, and there were few remains of herbaceous vegetation; those I recognised were chiefly of poppy, Potentilla, gentian, geranium, fritillary, Umbelliferae, grass, and sedges. On our arrival at the huts the weather was still fine, with a strong north-west wind, which meeting the warm moist current from the Ratong valley, caused much precipitation of vapour.
Cryptogamous acrogens: Acrogens: Mosses, equisetums, ferns, lycopodiums Lepidodendra. Dicotyledonous gymnosperms: Gymnogens: Conifers and Cycads. Dicotyledonous Angiosperms: Exogens: Compositae, leguminosae, umbelliferae, cruciferae, heaths, etc. All native European trees except conifers. Monocotyledons: Endogens.
But with respect to the seeds, it seems impossible that their differences in shape, which are not always correlated with any difference in the corolla, can be in any way beneficial; yet in the Umbelliferae these differences are of such apparent importance the seeds being sometimes orthospermous in the exterior flowers and coelospermous in the central flowers that the elder De Candolle founded his main divisions in the order on such characters.
But in regard to the differences both in the internal and external structure of the seeds, which are not always correlated with any differences in the flowers, it seems impossible that they can be in any way advantageous to the plant: yet in the Umbelliferae these differences are of such apparent importance the seeds being in some cases, according to Tausch, orthospermous in the exterior flowers and coelospermous in the central flowers, that the elder De Candolle founded his main divisions of the order on analogous differences.
Also stuck to the brown paper of the outer wrapper and mixed up with the Volucella's are a large number of other eggs, chalk white, spear-shaped and ridged lengthwise with seven or eight thin ribs, after the manner of the seeds of certain Umbelliferae. The finishing touch to their delicate beauty is the fine stippling all over the surface. They are smaller by half than the others.
It is a remarkable fact, as he justly observes, that the angiospermous exogens, which comprise four-fifths of living plants a division to which all our native European trees, except the Coniferae, belong, and which embrace all the Compositae, Leguminosae, Umbelliferae, Cruciferae, Heaths, and so many other families are wholly unrepresented by any fossils hitherto discovered in the Primary and Secondary formations from the Silurian to the Oolitic inclusive.
Primroses, cowslips, marsh violets, buttercups, wild-roses, cinquefoil, iris, and azure larkspur grow everywhere throughout the valley in the greatest abundance; and a peculiar species of umbelliferae, with hollow-jointed stems, attains in many places a height of six feet, and grows so densely that its huge serrated leaves hide a man from sight at a distance of a few yards.
These differences have sometimes been attributed to the pressure of the involucra on the florets, or to their mutual pressure, and the shape of the seeds in the ray-florets of some Compositae countenances this idea; but with the Umbelliferae it is by no means, as Dr. Hooker informs me, the species with the densest heads which most frequently differ in their inner and outer flowers.
And so it is with many species of Compositae and Umbelliferae, and indeed of all natural orders, some of which I have on the same day gathered in ripe fruit at 13,000 to 14,000 feet, and found still in flower at 9000 to 10,000 feet. From the middle of October to that of May, vegetation is torpid above 14,000 feet, and indeed almost uniformly covered with snow.
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