After Comparative Morphology, Cytology Chorology Species, Tetrap
Total Page：16
File Type：pdf, Size：1020Kb
Cytotaxonomic notes on some Galium species Galium boreale L. II (Taxonomy G. boreale L. and allied species) BY E. Kliphuis (Communicated by Prof. Dr. J. Lanjouw at the meeting of May 26, 1973) Summary of Comparative morphological investigation Galium boreale L. on herbarium specimen from different parts of the area confirmed the complexity of this species as stated by others. This is discussed. Based on fruit-indument characters it is concluded that four varieties can be distinguished. Introduction Galium boreale L. is a polymorphic species occurring on the northern hemisphere with a circumpolar distribution. Love and Love (1954), after studies of comparative morphology, cytology and chorology concluded that Galium boreale consist of two distinct species, viz.—a tetraploid 2(n =44) occurring in Europe to deep in Asiatic Russia and a hexaploid the 2(n =66) occurring on American continent and extending to within Eastern Asia. The tetraploid would be identical with Galium boreale as described by Linnaeus (1763), the hexaploid with Galium septentrionale as described by Roemer and Schultes in 1818. Urschler, (1955), accepting this conclusions recognized on fruit-indument character within Galium boreale L. the vars. boreale and hyssopifolium (Hofifm.) D.C. and within Galium septentrionale R. et S. the vars. septentrionale, incurvatum Urschl. and Urschl. Later revealed glabrum investigators the presence of hexaploid plants also in Europe besides tetraploids (Piotrowicz, 1961; Rahn, 1961; Kliphuis, 1973). These two cytotypes are morphological inseparable when using the combinations of characters considered critical by Love and Love (Rahn, 1961; Kliphuis, 1973). More extensive research involving biometry and cultivation—and crossing—experiments equally failed to furnish reliable characters by which to distinguish the two cytotypes (Kliphuis, 1973). The two cytotypes in Europe clearly belong The view Love and Love that to one species. of (1954) there are differences in morphology which are strictly associated with the ploidy level is untenable. However, this does not immediately mean that the possible existence of two species should be rejected. One could assume that there is an European-Asiatic taxon with 2n =44 and 2n =66 chromosomes 450 and an American-Asiatic one with, as far is known, 2n =66 chromosomes. (Up to now only hexaploids could be demonstrated within this area, Bocher and Larsen, 1950; Love and Love, 1954; Kara, 1956; Hxtlt&n, 1958; Lewis, 1962; Taylor and Brockman, 1966; Zhukova, 1967, 1969). As a matter of fact this is also the somewhat modified opinion by Love (1965) when he inspite of the results of the studies by Rahn (1961), continued to assume that the tetraploid is always the typical Eur- asiatic Galium boreale and the hexaploid always the typical American- Asiatic Galium septentrionale despite the supported possible occurrence of boreale like taxa in Southern and Eastern Europe and Siberia in which Rahn included of hexaploidy may occur. (l.c.) a study herbarium material collected in Europe, Asia and America. Using the combinations of charac- ters such as given by Love and Love, no good subdivision could be con- structed. It appeared that over the whole area of the species all characters in almost combination. occur every possible Rahn, therefore, rejects the view of Love and Love, but is unable to offer an alternative classification. The taxonomy of Galium boreale, as is clear, is still as confused as ever and this led the present author to a comparative morphological material the study of herbarium from whole area using also data obtained from experimental studies. Material the Herbaria Herbarium specimen from following were studied: Copen- hagen (C), Leningrad (LE), Leiden (L), Michigan, Ann Arbor (AFS. Mich.), Montreal (MTMG), Stockholm (S), and Utrecht (U). Results When comparing herbarium material of Galium boreale, the great variability of this species becomes obvious. It is seen in the stature, the mode of the branches, the shape of the panicle, the size of the leaves and flowers, the shape of the bracts, the indument, particularly the fruit indument. The situation is still far from clear as regards a possible correlation of the of of any these characters with geography the species. The only exception is the fruit indument. Four types of fruit indument have been observed; 1. Fruit with stiff- uncinate hairs. (Type I). 2. Fruits densely covered with patent, mostly silvery hairs. (Type II). 3. Fruits with curved hairs, mostly appressed, but sometimes more or less patent. (Type III). 4. Entirely glabrous fruits. (Type IV). These four types are given in fig. 1: a =type I; b =type II; c =type III; and d=type IV. 451 1 A 1 B 1 C 1 D Fig. 1. Four types of fruit-indument in Galium boreale L: A=fruit with uncinate hairs; B=with patent, straight hairs; C=with curved hairs; D=glabrous fruit. Fruits with the uncinate in the hairs of type (Type I) occur whole of Europe and adjacent parts of Asia to deep in Siberia. In America they are an exception (4 out of 342). Plants with the fruit hairs of the second and third type occur on the American continent. They were also observed in plants from eastern Asia. in In Glabrous fruits have been found the whole area. Europe they are 452 randomly distributed and occur side by side with plants with uncinate fruit indument. In America they seem to be restricted to a more or less limited area. between the in the A type intermediate second and third types occurs hairs the base and same area where those are found; straight at curved the but uncinate. These hairs toward tip, never can grow intermixed with third with both of these and ones of the second or type, or types vary less such sometimes from patent to more or appressed. In indument clearly uncinate hairs were observed. For the American continent the distribution of plants with different clear. To the localities fruit indument is not get a picture, of collections I is black have been mapped (see map 1). Type represented by a —, II III IV black dot. Type by an open triangle; Type by a cross; Type by a The shows the second and third occur the map types to throughout there is variation: there is increase of whole area, but some an plants with fruit hairs of the second type when going in west to northwest with clear in whereas III direction a accumulation Alaska, type becomes in with clear more frequent when moving an easterly direction a accumu- lation in the regions of the great lakes. Type IV has its greatest concen- tration in the area bordered by Lake Michigan, Lake Huron andLake Erie. The insufficient numbers of collections from Asia makes it impossible draw to conclusions on a possible distribution pattern of fruit indument that continent. types on Not much can be stated with regard to the density of the fruit indument, III there particularly concerning types I and where is a continiousvariation from with fruits. plants practically glabrous to plants very densely hairy Fruits falling under the second type are nearly always densely hairy. This situation is further complicated by differences in length and diameter become considerable from The of the hairs which may plant to plant. the in diameter: fruit hairs on same plant are fairly uniform length and they increase in size as the fruit matures. The panicle The panicle shape is extremely variable and grows from narrowly pyramidal or almost cylindrical with flowers clustered in glomeruli to very broadly pyramidal with distinct long pedicelled flowers. Many transistors of has been found thewhole occur. Theentire range variability throughout in 1: area. Examples of panicle shape are given photo narrowly pyramidal - - 1921. b a from a plant from Denmark, (A. Lange, s.n.) (C) and from U.S.A., Medicine Bow, Wy. (F. Petrak, 1950 s.n.) (S); normal pyramidal - D. - c from Denmark, (A. Hansen, 1961, 46) (C) and d from Canada, - Quebec. (FF. Marie - Victorin et Holland Germain, 1944. s.n.) (S); broadly pyramidal e - from Sweden, Halland, (C. Tillman, 1893, s.n.) (S) and f - from U.S.A., Decorah, Iowa, (E. W. D. Holway, 1884, s.n.) (S). E. KLIPHUIS: Cytotaxonomic notes on some Oalium species PLATE 1 pyramidal Narrowly Denmark, U.S.A. from C Iowa, North-America. panicle from and F and Europe pyramidal in Sweden L. normal from boreale U.S.A.; E Galium panicle of Wyoming, shape from pyramidal B panicle broadly in Denmark, Canada; variability from --— same plant Quebec, a- — the from from of A Example D panicle 1. Photo PLATE 2 Neum.); year one arenosum soil, peaty (f. on Sweden B. as in plant collected same plant the cultivation). C. a of from year A sandy-clay; (fourth specimen on Voucher cultivation of transplantation L. year boreale after third Galium Denmark of from Phenoplasticy plant a 2. from Photo B. 453 Galium boreale the North-American Distribution pattern of on continent. plants -indument with uncinate fruit (Type I); ∆ with straight hairs (Type II); X with with curved hairs (Type III) and • glabrous fruits (Type IV). THE BRACTS from obtuse to in the The bracts range circular-ovate, oblong, acute sometimes whole area. The two extremes even occurring on the same plant. 454 The leaves The leaves are in whorls of four; trinerval and highly variable in length and width. The greatest differences were observed in plants from north- east Asia where both plants with liniar leaves and plants with elleptical- oval leaves and also all intermediate forms. In other occur, possible less The regions the extremes are much pronounced. general impression that America and leaves than is plants in possess longer narrower plants the other in Europe. Within Europe on hand plants from Sweden, Norway, Russia be Finland, and northern seem to longer and narrower leaved than from other whereas from Iceland plants parts, plants appear to have the smallest leaves.