| Species. | Altitude of station in feet. | General distribution. |
|---|---|---|
| Schizæa robusta, Bak. | 3,000-6,000 | Perhaps a form of S. australis, Gaud., from the Falkland and Auckland Islands. |
| Polypodium serrulatum, Mett. | 3,000-6,000 | Generally diffused in the tropics and subtropics. |
| Aspidium caryotideum, Wall. | In the forests | Himalayas, South Africa, &c. |
| Aspidium filix mas, Sw. | In the highlands | Over four continents, from the arctic circle to the higher levels of tropical mountains. |
| Asplenium trichomanes, L. | 5,000-8,000 | Temperate zones and the higher levels of tropical mountains. |
| Asplenium monanthemum, L. | 3,000-6,000 | American Andes, Madeira, Tristan d’Acunha, Azores, Abyssinia, &c. |
| Asplenium fragile, Presl. | 4,000-6,000 | Andes. |
| Asplenium contiguum, K. | 2,000-5,000 | Lord Howe Island, Ceylon, Neilgherry Hills. |
| Asplenium adiantum nigrum, L. | 4,000-10,000 | Europe, Asia, Africa, Atlantic Islands. |
| Asplenium aspidioides, Sch. | 1,000-6,000 | Andes, Africa, India. |
NOTE 66 (page [226])
Endemic Genera of Ferns in Hawaii
Hillebrand gives two genera of ferns peculiar to Hawaii, one, Sadleria of Kaulfuss, “scarcely distinct from Blechnum,” and containing four species; the other, Schizostege, constituted by himself, and represented by a single species found in only one or two of the islands.
NOTE 67 (page [241])
On the Dispersal of Compositæ by Birds
The goldfinch’s habit of pecking at the heads of thistles, and pulling out the achenes in bundles, is well known. Gätke mentions two suggestive instances of birds feeding on the fruits of a Composite plant. According to this observer, the Scarlet Grosbeak (Pyrrhula erythrina), when it alights on Heligoland, always feeds on the achenes of Sonchus oleraceus, which it picks off the plant; whilst the Parrot Crossbill (Loxia sp.), feeds in Heligoland on burrs and thistles (Heligoland as an Ornithological Observatory, pp. 407, 409). See [Note 91].
NOTE 68 (page [264])
On some of the Hawaiian Endemic Genera, excluding those of the Compositæ and Lobeliaceæ
Haplostachys, Phyllostegia, and Stenogyne, all Labiate Genera.—Phyllostegia is not strictly peculiar to Hawaii, since out of the 17 species enumerated in the Index Kewensis, 15 are Hawaiian, 1 Tahitian, and 1 is accredited to Unalaska (one of the Aleutian Islands). The last locality appears to be an error. The species in question is P. microphylla, Benth.; and on looking up the original authority in Linnæa (vi. 570, 1831), I find the locality is thus given: “insula coralligena Romanzoffii,” which is either one of the atolls of the Paumotu Islands in about lat. 15° S. and long. 144° W., or a coral island of the Marshall Group, most probably the former.... I paid some attention to the suitability of the fruits of these three Labiate genera for dispersal by frugivorous birds, for which the fleshy nucules in the cases of Phyllostegia and Stenogyne apparently fit them. Out of the fruits of five species of Phyllostegia examined by me, the seed-coverings in three species, after the removal of the fleshy covering of the nucule, were too soft for the protection of the seed in a bird’s stomach. Hillebrand also observes (p. 347) that the nucules when dried are wrinkled, and absorb moisture easily, a quality which, if true of all the species, would make the distribution of the genus by birds impossible. However, in two species I found the seed-coverings somewhat harder. It would seem that since birds have largely ceased to disperse these plants, the soft-skinned nucules would in the absence of their selective agency more frequently characterise the genus. It is possible that the dry nucules of Haplostachys, which according to Hillebrand are not affected by drying, represent the original condition of those of Phyllostegia, and that the fleshy character has been acquired in this archipelago. It will be seen in the list on page [263], that Haplostachys is regarded by Gray as a section of Phyllostegia. The remarks under Phyllostegia, regarding the softness of the seed-coverings beneath the fleshy coat of the nucule, also apply to Stenogyne; and Hillebrand, in contrasting its fleshy nucules with the dry nucules of Haplostachys, implies that they absorb water, which, I may remark, would render them quite unfit for dispersal by frugivorous birds.
Touchardia (Urticaceæ).—According to Hillebrand, the solitary species is by no means common in the group now. In 1897 I found it growing abundantly some miles up the Waipio gorge, Hawaii.
Cheirodendron (Araliaceæ).—C. Gaudichaudii, the well-known “Olapa” tree, is common in the forests of all the Hawaiian Islands between 2,000 and 5,000 feet; but I noticed it occasionally at greater elevations, as on the south-east slopes of Mauna Kea, where it extends to 7,000 feet. As described on page [343], the “Olapa” often grows in close contact with the Lehua (Metrosideros polymorpha), the two trunks appearing as one. The drupes would attract frugivorous birds and the pyrenes are well adapted for this mode of dispersal. Mr. Perkins states that the drupes are much sought after by the various species of Phæornis, a genus of birds peculiar to Hawaii.
Deterioration of Fruits for Purposes of Dispersal.—Among fruits or endemic genera that have evidently deteriorated in the Hawaiian Group as far as fitness for dispersal is concerned, may be mentioned, in addition to those of Phyllostegia and Stenogyne above noticed, those of the Araliaceous genera, Pterotropia and Triplasandra, and the Amarantaceous Nototrichium. The pyrenes of the first two genera on account of their thin covering, and the seed of the last-named genus on account of its thin testa, seem ill-fitted now for transport in a bird’s stomach, yet we cannot doubt that their ancestors originally arrived in this fashion. The same principle is also illustrated by some Hawaiian non-endemic genera of later eras that possess peculiar species, such, for instance, as in the case of Elæocarpus discussed in [Chapter XXVI.]