Proceedings of the American Association for the Advancement of Science/v039/F/The distribution of Hepaticæ of North America
| The distribution of Hepaticæ of North America. |
| By Lucien M. Underwood, Syracuse N. Y. |
The committee who arranged this series of papers on the distribution of North American plants could not have been aware of the fragmentary knowledge we possess of the distribution of the Hepaticæ in North America, otherwise this paper of the series would certainly have been omitted. There is possibly no other major division of plants of which we know so little of the range of species in latitude, in longitude, or in altitude. A few small areas of our country have been more or less carefully studied. The White Mountain region, the southern portions of New England, the region of Central New York, of Northern New Jersey, of Central Ohio, a few counties of Illinois, the District of Columbia, parts of the Appalachian region, small ares of Florida and the environs of San Francisco have been examined but not exhausted by American collectors. Over the greater portion of our region the higher vegetation has been taken and the hepatics left. Of the hepatic flora of Louisiana, Texas and the great southwest almost nothing is known; over the greater portion of Florida and the Gulf region the collector of hepatics has never wandered; the Rocky Mountains, the Sierras, and the rich bryophytic regions of Oregon and Washington have never yet had their hepatic treasures revealed, and the same is true of many other portions of our country. In the provinces north of the United States much larger collections have been made, mainly through the untiring energy of Prof. John Macoun, and from the borderland of these possessions, Mr. Leiberg has already sent enough material to disclose the presence of an extensive hepatic flora frin the region of Pend d'Oreille. The straggling and scanty collections gathered here and there over the country must form the basis for what can be only a paper of preliminary notes on the distribution of the American Hepaticæ, for a large collection of American species has not yet been brought together. The Austin collection is probably the largest in existence, but no American botanist has seen it since its purchase by Messrs. Carrington and Pearson of Manchester, England. My own, probably the next in size, has been largely accumulated since 1885 and is doubtless the largest on this continent, but Is still lacking in a number of the described species and can furnish only fragmentary data on matters of distribution. The only public collection of considerable size in the country is that preserved at the Gray Herbarium, but aside from the Sullivant collection, it contains in American material only the published exsiccatæ of Austin and Wright.1 It is interesting to learn that the Torrey Herbarium has recently received from Mr. Pearson some of the types of Austin's species which hitherto had not been represented in any collection in this country.
1 It should not be forgotten that the Gray Herbarium contains the extensive Taylor collection, containing valuable material mainly European and exotic. It contains, however, some of the types of Taylor's American species and has, therefore, some local value. In general value it ranks with the large collections of the world.
In thus advertising the poverty of material on hand we hope to impress on botanists the desirability of making local collections which, if centralIzed, will serve In future for work in this direction.
How far this local collection is a necessity is thoroughly illustrated by the fact that every corner hitherto explored brings to light new and unexpected forms. A large number of species accredited to America are known only from the specimens which Austin collected in the vicinity of Closter, N. J., and careful searching in other regions will furnish others of equal interest. Here in Central New York we have recently picked a Lejeunea (L. Austini) which hitherto had not been found north of the Carolinas. Jungeermania exsecta, more commonly found in mountain regions, grows with other northern plants like Ribes lacustre about the cold springs of our “Scolopendrium Lake,”2 while Fimbriaria tenella fruits in profusion on our warmer lowlands, coming among us like Listera australis from a lower latitude arid a warmer clime.
2 Jamesville, N. Y., where a number of northern plants may be found In the cold ravine about Green Pond.
The task then assigned us can be performed only by marking out a few rude outlines, taking ground tentatively rather than dogmatically and suggestlug probablllties rather than stating facts.
The group of Hepaticæ as described from the entire world includes above twenty-five hundred species.1 In order to give some general idea of the distribution of the group as a whole, we have selected two of the larger genera Frullania and Plagiochila whose distribution is peculiarly widespread; they are further selected as representative types of the two great tribes of the Jungermaniaceæ,2 itself the largest and most highly differentiated of the orders of the Hepaticæ.
1 In the Synopsis Hepaticarum (1844-7) are 1641 species. As no general summary has since been published, an estimate is difficult. Additions have been numerous and some idea will be furnished by noting the increase of certain genera. Frullania, according to our count, has increased from 155 to 215 species. Radula from 40 to 120 (cf. Stephani, Hedwigia, XXIII, 156, 1884) and Bazzania from 63 to 167 (cf. Stephani, Hedwigia, XXV, 238, 1886). These data would seem to place the above estimate too low rather than too high.
2 Cf. Spruce, Hepaticæ of the Amazon (1885).
From the showing on the following table, which will not unfairly represent the entire hepatic flora, we may derive certain general concluslons:—
1. As among all cryptogams the tropics are most prolific in species, and the profusion is said by travellers to be equally marked.
2. The hepatic ftora of the southern hemisphere is proportionally more extensive than that of the northern.
3. The insular flora, especially in the southern hemisphere, is a marked feature. The percentage of endemic species is also marked. Of the forty-seven Javan species of Plagiochila only fourteen are found elsewhere. Of the twenty-two New Zealand species all but four are endemic.
4. In continental areas those possessing abundant forest growth, combined with excessive humidity and high temperature, are most likely to be proific In Hepaticæ. The valley of the Amazon and the eastern slope of the Andes fully meet these conditions, as the results of the long continued travels of Dr. Spruce have abundantly demonstrated.1
Countries bordering on warm seas where the prevailing winds are shoreward, and the rainfall is considerable, are also favorable regions for the development of this group. Certain portions of Mexico and the Himalaya region seem to possess these conditions.
The close connection of the bryologic flora of both continents of the northern hemisphere has been often remarked. It will, therefore, not be surprising to learn that among the 265 species of hepatics known from America, north of Mexico, 127 are also found In Europe, and the proportion of species common to the two continents regularly increases as we pass northward into the boreal regions of North America.
From Mexico 212 species have been reported2 of which only a small portion are of species growing farther north, a condition likely to be changed when the hepat1c flora of the southwest shall be made known.
Europe, with 325 species, shows the effect of the early work of Hooker, Nees, Gottsche, Lindenberg and Taylor, supplemented by the later labors of Spruce, Pearson, Massalongo, Stephani, Limpricht, Jack, Lindberg and numerous other workers, and even in that well-developed region new forms are constantly coming to light.
1 Over 550 species are described in his Hepaticæ of the and of the Andes of Peru and Ecuador, of which a large proportion are new.
2 Seq. Gottsche, De Mexikanske Levermosser (1863).
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| TABLE SHOWING DISTRIBUTION OF THE HEPATIC GENERA, FRULLANIA AND PLAGIOCHILA.1 |
| Frulliania | Plagiochila | ||
| North America |
North of Mexico. | 21 | 0 |
| Mexico. | 29 | 69 | |
| West Indies. | 19 | 52 | |
| South America |
Bolivia. | 8 | 25 |
| Brazil. | 39 | 35 | |
| U. S. Columbia. | 15 | 29 | |
| Chile. | 10 | 15 | |
| Ecuador. | 25 | 44 | |
| Guiana. | 12 | 13 | |
| Patagonia. | 3 | 12 | |
| Paraguay. | 2 | — | |
| Peru. | 23 | 41 | |
| Venezuela. | 6 | 8 | |
| Total. | 79 | 155 | |
| Europe | 8 | 8 | |
| Asia (Mostly from India.) | 15 | 14 | |
| Africa (Mostly Cape Colony.) | 14 | 21 | |
| Australia. | 12 | 9 | |
| Tasmania. | 6 | 8 | |
| New Zealand. | 11 | 22 | |
| Java. | 23 | 47 | |
| Borneo. | 4 | 7 | |
| Sandwich Islands. | 9 | 6 | |
| Isles of Indian Ocean. | 6 | 12 | |
| Atlantic Isles. | 6 | 3 | |
| Pacific Isles. | 13 | 18 | |
1 It should be noted that certain regions have been better worked than others, which will account for apparent anomalies. For the two genera North America may be considered as fairly represented. In South America the excess noted In Brazil, Ecuador and Peru, is due to the labors of Dr. Spruce. The excess in Java is due to the labors of Blume, Nees and Sande-Lacoste.
A few comparisons of the hepatic flora of the two continents will prove suggestive; we select only the larger genera.
| COMPARISON OF HEPATIC FLORA OF EUROPE AND NORTH AMERICA. |
| Genera. | Europe. | Common to Europe and America. |
N. America (North of Mexico). |
Common to United States and Mexico. |
Mexico. |
| Lejeunea. Frullania. Bazzania. Plagiochila. Scapania. Porella. Lophocolea. Radula. Cephalozla. Jungennania. Anthoceros. Riccla. Fimbriaria. |
14 8 5 8 22 7 10 8 24 68 4 20 7 |
4 2 2 2 7 5 4 1 8 19 2 9 3 |
23 21 2 6 13 9 7 10 13 35 12 20 7 |
1 3 — — 1 2 1 2 — 3 2 1 1 |
83 29 11 68 1 15 8 11 2 16 5 2 2 |
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Aside from the dozen or more ubiquitous species, all of which are common in Europe, the species of North American Hepaticæ may be arranged in four floral regions or provinces. These were first outlined in our first venture at the study of our species1 and further information has tended to strengthen the belief that they are fairly natural ones, with only such transitional forms as are common wherever lines are attempted on the face of Nature. These provinces are as follows:—
I. Boreal.—Including the cooler regions of North America from the latitude of Lake Superior northward, including Labrador, Alaska and Greenland, and extending southward on the higher mountains of New England and, so far as scanty information goes, the mountains of Colorado also. A small collection of Labrador species made by Prof. O. D. Allen shows a striking similarity with the species of the White Mountain flora, as do those from Gaspé, Quebec, communicated by the same collector. In this province occur principally species of Scapania, Marsupella, Jungermania, Mylia and Gymnomitrium with a few of Frullania and Cephalozia. The first-named genera are notoriously boreal, only one species of Scapania extending far southward and that one (S. undulata) appearing as far as the mountain region of Mexico. The great majority of the species are also inhabitants of Northern Europe and probably of Asia as well.
1 Descriptive Catalogue of North American Hepllticæ (1884), pp. 4, 5.
II. Medial.—This province includes the range of northern states from Nova Scotia and lower Ontario to the Rocky Mountains, extending southward to Arkansas and the Carolinas. From the fact that this province includes nearly all the portions of our country that have been most carefully studied, the number of species from this province is greatly in excess of others, including nearly half of our known flora. The range of genera is also very great, including all but seven of the fifty-three now known from the conntry.1 The Marchantiaceæ and Ricclaceæ are especially well represented.
1 Plates illustrating forty-six genera appear in the sixth edition of Gray's Manual of Botany.
III. Austral.—Thls province includes the states bordering ou the Gulf of Mexico, reaching northward along the lowlands of Georgia and South Carolina. A single trip of Mr. Austin and Capt. John Donnell Smith with a few collections by Dr. C. Mohr from the vicinity of Mobile, have furnished us nearly all the information we possess of this province,1 and yet it is sufficient to indicate the existence of a striking flora, bearing, as might be expected, the marks of the West India region. Much may be expected from the swamps of Florida so soon as some one may be induced to collect the bryologlc treasures of what ought to be one of the richest hepatic regions of the continent. Species of Frullania, Lejeunea, Radula and the southern types of Plagiochila and Porella are the characteristic forms, as well as Dumortiera, Anthoceros, Sphærocarpus and the rare and peculiar Thallocarpus. More endemic species are found here than farther northward, yet there are interesting relations suggested with the flora of the Mediterranean region of the Old World.