Contributions to the morphology, synonymy, and geographical distribution of arctic plants / by Theo. Holm.

  • Holm, Theodor (Herman Theodor), 1854-1932.
Date:
1922
Catalogue details

Licence: In copyright

Credit: Contributions to the morphology, synonymy, and geographical distribution of arctic plants / by Theo. Holm. Source: Wellcome Collection.

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    They constitute a very natural little family; with the exception of Pyrola grandiflora and the typical P. rotundifolia, they are sylvan types and they often grow associated with each other forming small colonies; reproduction by means of root-shoots is characteristic of several of the species. We have seen from the geographical table (Table 6) how Pyrola minor extends clear across the northern hemisphere, reaching the arctic regions on this continent, including Greenland, in Scandinavia, and in Russia; a similarily wide distribution is exhibited by P. rotundifolia, it being absent only from our arctic coast, Greenland, and Iceland, and by P. secunda which is absent from the northeastern corner of Asia: Terra Tschuktchorum and Kamtchatka. Then with regard to Moneses] this shows the same distribution as P. secunda but is absent from Caucasus. Finally, P. chlorantha is absent from ten of the eighteen districts enumerated on the table, namely: our north coast, Greenland, Russia, Siberia, and Iceland, but it is represented in Europe from Finmark south to the Alps and the Pyrenees. We have thus four species of a remarkably wide distribution in both Worlds. Nevertheless, the Pyrolaceae are best represented on this continent, the home of three species of Chimaphila, besides oi Pyrola elliptica, P. picta, P. chirnaphil- oides, and P. aphylla, and the foliage of the last three species resembles that of Chimaphila more than that of Pyrola; in Europe there is a somewhat isolated type: P. media. It is interesting to notice that while P. chlorantha is absent from Asia, Maximowicz ^ discovered a near ally of it, P. renifolia, in coniferous woods in the Amur district where, moreover, P. secunda, P. rotundifolia, Mon- eses,. and Chimaphila umbellata were collected. It would thus appear as if the centre of the Pyrolaceae might have been located on this continent, rather than in the Old World, inasmuch as the Mono- tropeae, the nearest allied family, are also best represented here, with seven mostly monotypic genera of which Monotropa is the only genus occurring also in Europe. , However, when we bear in mind that P. mmor and typical P. rotundifolia are much more abundant in Europe than on this continent, it might be more orrect not to include them in the American element, I mean the element which presumably originated on this continent. With respect to P. chlorantha it seems difficult to combine its distribution in Europe with that on this continent and, as stated above, it is absent from all of Asia. The occurrence of Chimaphila umbellata in Europe causes also some difficulty but its distribution in Asia, Altai for instance, may point towards a former, much wider distribution, at present disconnected. Taking all points into consideration it seems a most difficult task to treat the distribution of this singular little family, almost exclusivel}^ confined to the temperate regions of both Worlds, and being mostly sylvan types. For whether their centre of distribution, or let us say development, be placed on this con¬ tinent or in Europe, the question will necessarily arise how these little plants have remained so unchanged on both continents when, as stated b}^ Darwin,^ ^Ty comparing the now living productions of the temperate regions of the New and Old Worlds, we find verj^ few identical species, but we find in every great class many forms, which some naturalists rank as geographical races, and others as distinct species; and a host of closely allied or representative forms which are ranked, by all naturalists as specifically distinct.’’ With respect to the Pyrolaceae some certain ‘^geographical races” have become developed, notably of Chimaphila umbellata, Pyrola secunda, and P. rotundifolia, but, nevertheless, the typical species are represented in both Worlds. Otherwise with respect to the plants with which they are associated. 1 Primitiae Flor. Amur. l.c. p. 190. 2 Origin of Species, p. 441.