CHROMOSOMES AND RELATIONSHIPS OF KOENIGIA ISLANDICA
The species Koenigia islandica L. may be assumed to be the most hardy of all annuals, since it occurs at higher altitudes and latitudes than any other therophyte. Its area of distribution, restricted to the Arctic, though with offshoots to some temperate mountains, is practically circumpolar. In Asi...
| Published in: | Canadian Journal of Botany |
|---|---|
| Main Authors: | , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Canadian Science Publishing
1957
|
| Subjects: | |
| Online Access: | http://dx.doi.org/10.1139/b57-044 http://www.nrcresearchpress.com/doi/pdf/10.1139/b57-044 |
| Summary: | The species Koenigia islandica L. may be assumed to be the most hardy of all annuals, since it occurs at higher altitudes and latitudes than any other therophyte. Its area of distribution, restricted to the Arctic, though with offshoots to some temperate mountains, is practically circumpolar. In Asia, it has long been known from the Tien Shan at about 40° lat. N. In Europe, its southern limits are on the Isle of Skye at about 50° 30′ lat. N., while in North America its southernmost locality was a little north of Jasper in the Canadian Rockies until its discovery a few years ago in Colorado just south of the 40th parallel. A closely related species is known to occur in the southern parts of Tierra del Fuego. Specimens from the Faeroes, Greenland, Iceland, Scandinavia, and Colorado are morphologically and cytologically inseparable, being characterized by the tetraploid chromosome number 2n = 28. Though the genus is usually regarded as mono- or bi-typic, (1) it is pointed out that some species, often included in Polygonum s.lat., really belong to Koenigia in a somewhat wider sense; in addition to morphological similarities, they are characterized by the basic chromosome number x = 7, which is rare in the family and absent in the Polygoneae s.str. (2) It is also emphasized that the division of the Polygonaceae into subfamilies has not been successful since evolutionary highly distinct types are traditionally united in the subfamily Polygonoideae. (3) It is proposed that this subfamily be divided into two large subfamilies at the same time as Koenigia and its closest relatives be treated as a separate taxon at a very high level. |
|---|