scholarly journals Évaluation de l'activité biologique du Ledum groenlandicum Retzius /

2006 ◽  
Author(s):  
Dominic Dufour
Keyword(s):  
Ledum Groenlandicum

The vegetation and chemical properties of patterned fens in the Swan Hills, north central Alberta

1975 ◽  
Vol 53 (23) ◽  
pp. 2776-2795 ◽  
Author(s):  
D. H. Vitt ◽  
P. Achuff ◽  
R. E. Andrus
Keyword(s):  
Picea Mariana ◽  
Vascular Plants ◽  
Chemical Properties ◽  
Vegetation Patterns ◽  
North Central ◽  
Water Flows ◽  
Sphagnum Magellanicum ◽  
Ledum Groenlandicum ◽  
Menyanthes Trifoliata ◽  
And Chemical Properties

Three patterned fens in north central Alberta were analyzed to elucidate vegetation patterns in vascular plants and bryophytes. Two flark associations dominated by Menyanthes trifoliata and Carex limosa, both of which had Sphagnum jensenii and Drepanocladus exannulatus phases, were recognized. The strings consist of two associations; one is dominated by Betula glandulosa, Tomenthypnum falcifolium, and Aulacomnium palustre; the second is dominated by Picea mariana, Sphagnum magellanicum, and Ledum groenlandicum. An intensive analysis of one fen reveals that these mires are ‘poor fens’ with a mean pH of 5.2 and Ca2+concentration of 2.3 ppm. The fens occur on low drainage divides and Ca2+ is depleted as water flows through the fens. An ecological series of bryophytes is described in the transitions between flarks and strings.

Flower cold hardiness: a potential determinant of the flowering sequence exhibited by bog ericads

1979 ◽  
Vol 57 (9) ◽  
pp. 997-999 ◽  
Author(s):  
R. J. Reader
Keyword(s):  
Low Temperatures ◽  
Cold Hardiness ◽  
Vaccinium Macrocarpon ◽  
Southern Ontario ◽  
Air Temperatures ◽  
Insect Pollinators ◽  
Cold Hardy ◽  
Vaccinium Myrtilloides ◽  
Potential Determinant ◽  
Ledum Groenlandicum

In laboratory freezing trials, cold hardiness of six types of bog ericad flowers differed significantly (i.e., Chamaedaphne calyculata > Andromeda glaucophylla > Kalmia polifolia > Vaccinium myrtilloides > Ledum groenlandicum > Vaccinium macrocarpon) at air temperatures between −4 and −10 °C but not at temperatures above −2 °C. At the Luther Marsh bog in southern Ontario, low temperatures (−3 to −7 °C) would select against May flowering by the least cold hardy ericads. Availability of pollinators, on the other hand, would encourage May flowering by the most cold hardy species. Presumably, competition for insect pollinators has promoted the diversification of bog ericad flowering peaks, while air temperature, in conjunction with flower cold hardiness, determined the order in which flowering peaks were reached.

TWO NEW MACROSIPHINI (HOMOPTERA: APHIDIDAE) FROM MANITOBA

1973 ◽  
Vol 105 (5) ◽  
pp. 813-815 ◽  
Author(s):  
A. G. Robinson
Keyword(s):  
New Species ◽  
Potentilla Fruticosa ◽  
Two New Species ◽  
Ledum Groenlandicum

AbstractTwo new species of aphids are described from Manitoba, Acyrthosiphon assiniboinensis new species from Potentilla fruticosa L., and Masonaphis pinawae new species from Ledum groenlandicum Oeder.

scholarly journals Observations sur les buttes organiques de la Côte-Nord du golfe du Saint-Laurent, Québec

2007 ◽  
Vol 42 (3) ◽  
pp. 289-301 ◽  
Author(s):  
Jean-Claude Dionne ◽  
Vincent Gérardin
Keyword(s):  
Empetrum Nigrum ◽  
Rubus Chamaemorus ◽  
Ledum Groenlandicum

RÉSUMÉ Divers types de buttes organiques de taille décimétrique à métrique, non encore décrites, ont été observés sur la Côte-Nord du golfe du Saint-Laurent entre Sept-Îles et Blanc-Sablon. Les unes sont entièrement organiques, d'autres ont un noyau minéral constitué d'un bloc erratique. Certaines buttes sont composées de débris organiques peu à moyennement décomposés, en particulier des débris d'éricacées et des bryophytes dont principalement des sphaignes. D'autres sont composées d'une "tourbe" ligneuse et sèche. Sur les premières, le couvert végétal comprend Kalmia augustifolia, Rhododendron canadense, Ledum groenlandicum, Vaccinium spp., des sphaignes et des lichens. Sur les secondes, on trouve en surface Empetrum nigrum, Vaccinium spp., Ledum groenlandicum, Rubus chamaemorus et des lichens (Cladonia spp. et Cladina spp.). Les buttes forment tantôt des champs ouverts, tantôt des complexes où elles sont très rapprochées. On les trouve généralement sur des versants de pente faible à modérée, relativement bien drainés. Plusieurs se sont développées directement sur le substrat rocheux; quelques-unes sont sur du till, des plages sablo-graveleuses ou sur des dunes. Les buttes ne sont pas gelées en été et ne ressemblent en rien aux palses. Dans la plupart des sites, elles semblent s'être développées après feu. Le mode de formation paraît lié à l'accumulation différentielle sur place de débris organiques à partir d'îlots de végétation, en particulier des éricacées, dont Kalmia augustifolia. Certaines buttes avec un bloc erratique pourraient résulter en partie du soulèvement de pierres par le gel. D'autres buttes à contenu organique ligneux se seraient développées sur place en raison de l'humidité ambiante. L'âge des buttes est postérieur à 3000 ans BP. Plusieurs se sont développées après 1500 ans. Le taux d'accumulation de la matière organique estimé pour certaines buttes varie de 0,38 à 3 mm par année.

Photosynthetic Adaptations in Bog and Alpine Populations of Ledum Groenlandicum

Ecology ◽  
1981 ◽  
Vol 62 (3) ◽  
pp. 579-586 ◽  
Author(s):  
John F. Riebesell
Keyword(s):  
Ledum Groenlandicum

Post-pollination callose development in ovules of Rhododendron and Ledum (Ericaceae): zygote special wall

1984 ◽  
Vol 69 (1) ◽  
pp. 127-135
Author(s):  
E.G. Williams ◽  
R.B. Knox ◽  
V. Kaul ◽  
J.L. Rouse
Keyword(s):  
Periodic Acid ◽  
Embryo Sac ◽  
Aniline Blue ◽  
Blue Fluorescence ◽  
Callose Deposition ◽  
Periodic Acid Schiff ◽  
Callose Wall ◽  
Unfertilized Ovules ◽  
Ledum Groenlandicum

In Rhododendron spp. and Ledum groenlandicum a callose wall is laid down around the zygote in the first 2 days after fertilization. The periodic acid/Schiff-positive, aniline blue-fluorescence-positive callosic wall is initiated adjacent to the degenerating synergid, extends to cover the entire zygote surface, and remains visible during the initiation of embryogeny as the zygote elongates before the first proembryonal division. Unfertilized ovules show eventual callose deposition in the ovule wall cells during senescence in undeveloped abscising pistils, but show no development of callose within the embryo sac. Possible roles of a zygote special callose wall are discussed.

Lodgepole pine/Labrador tea type communities of western Canada

2002 ◽  
Vol 80 (2) ◽  
pp. 151-165 ◽  
Author(s):  
W L Strong
Keyword(s):  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Inverse Correlation ◽  
Yukon Territory ◽  
Western Canada ◽  
Different Types ◽  
Successional Species ◽  
Labrador Tea ◽  
The Common ◽  
Ledum Groenlandicum

Lodgepole pine/Labrador tea (Pinus contorta Dougl. ex Loud. var. latifolia/Ledum groenlandicum Oeder) relevés were classified and characterized based on data from archival sources (n = 428). Eleven forest communities were recognized and were distinguished by the relative dominance of Sphagnum, Cladina and Cladonia, Lycopodium, Vaccinium species, or feathermosses. Picea mariana (Mill.) BSP was the common secondary successional species. Most paired-community comparisons were nonoverlapping in ordination space, although intermingling sometimes occurred along interfaces. Lodgepole pine/Labrador tea stands occurred on upland sites within the boreal–cordilleran ecoclimatic transition zone along the eastern slopes of the Rocky Mountains from southwestern Alberta to the southern Yukon Territory. Nine communities had mesic to subhygric moisture and submesotrophic to mesotrophic nutrient regimes. The exceptions were a Pinus contorta/Ledum groenlandicum/Sphagnum (wetter sites) and a Pinus contorta/Ledum groenlandicum/Cladina mitis (drier sites) community. An inverse correlation occurred between latitudinal location and elevation of occurrence (r = –0.56, P < 0.001, n = 403) with a northward decline of 65 m/100 km. The concept of a "type community" is proposed for formally documenting the composition of plant communities and optimizing the comparability of different types. Eight of the recognized communities fulfilled the proposed criteria for a type community and two were considered provisional types.Key words: vegetation classification, Pinus contorta, Ledum groenlandicum, type community.

Contribution of overwintering leaves to the growth of three broad-leaved, evergreen shrubs belonging to the Ericaceae family

1978 ◽  
Vol 56 (10) ◽  
pp. 1248-1261 ◽  
Author(s):  
R. J. Reader
Keyword(s):  
Growing Season ◽  
Leaf Nitrogen ◽  
Leaf Nitrogen Content ◽  
Nitrogen And Phosphorus ◽  
Southern Ontario ◽  
Plant Parts ◽  
Mature Leaves ◽  
Growing Seasons ◽  
Labrador Tea ◽  
Ledum Groenlandicum

Individual leaves of three bog ericads, leatherleaf (Chamaedaphne calyculata), bog laurel (Kalmia polifolia), and Labrador tea (Ledum groenlandicum), were retained for a maximum of two growing seasons in a peat bog in southern Ontario. The premature loss of mature leaves, resulting from artificial defoliation, significantly reduced the growth of new shoots of L. groenlandicum and K. polifolia but not of C. calyculata. Defoliation effects were directly proportional to the normal retention time for overwintering leaves. Mature leaves probably translocate photosynthate, nitrogen, and phosphorus to other plant parts. This would explain why leaf dry weights were greatest at the start, rather than at the end, of the leaves' second growing season. Net photosynthetic rates decreased with leafage, but in terms of leaf nitrogen content, new and old leaves fixed equal amounts of carbon.

Antioxidant, anti-inflammatory and anticancer activities of methanolic extracts from Ledum groenlandicum Retzius

2007 ◽  
Vol 111 (1) ◽  
pp. 22-28 ◽  
Author(s):  
Dominic Dufour ◽  
André Pichette ◽  
Vakhtang Mshvildadze ◽  
Marie-Eve Bradette-Hébert ◽  
Serge Lavoie ◽  
...  
Keyword(s):  
Anticancer Activities ◽  
Methanolic Extracts ◽  
Anti Inflammatory ◽  
Ledum Groenlandicum
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