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In the Colorado Front Range Kobresia bellardii distribution is restricted to alpine meadows which are neither extremely wind exposed nor buried under snow in winter. This study examined reasons for such a limited distribution by comparing the behavior of undisturbed Kobresia with that of transplants into alpine habitats with less and more winter snow accumulation. Kobresia's success in snow—free meadows was related to rapid summer growth and to its use of an extended period for development, from about 1 April to 20 October. New leaves began elongation in the autumn and completed growth the following summer. Most carbohydrates were stored as oligosaccharides in the shoots. During periods of relatively warm weather (>—4°C) in winter, when soil water potential (ψs) rose above —2.0 MPa, leaves elongated slightly; they died back when cold, windy weather resumed. Kobresia did not survive in a fellfield primarily because of mechanical damage by windblown snow and sand. Low ψs led to leaf wilting in summer and winter. Shallow snow cover (°15 cm) that melted early permitted extensive April leaf elongation in saturated soils. The prematurely developed leaves apparently lost frost hardiness and were injured in late spring freezes. In sites of moderate (°75 cm) and deep (°140 cm) snow accumulations, autumn dieback was incomplete when drifts first formed in September and October. Winter freezing destroyed the apparently unhardened leaf tissues and meristems, resulting in loss of carbohydrate reserves. In the moderate snow accumulation sites, leaf elongation was delayed until snowmelt was complete in late June or early July. Interspecific competition appeared unimportant in determining Kobresia distribution. Flower and seed production were reduced up to 99% by habitat alteration. Kobresia may not be reproducing by seed in the Front Range at the present time.

Recent studies have shown that mutations in the glucokinase gene on chromosome 7 can cause an autosomal dominant form of NIDDM with a variable clinical phenotype and onset during childhood. The variable clinical phenotype includes mild fasting hyperglycemia (i.e., a plasma glucose value of >110 mg/dl, a value that is at least 2 -3 SDs above normal), impaired glucose tolerance, gestational diabetes mellitus, as well as overt NIDDM as defined using National Diabetes Data Group or World Health Organization criteria. Because gestational diabetes mellitus was a clinical feature associated with glucokinase mutations, we have screened a group of women with gestational diabetes who also had a first-degree relative with diabetes mellitus for the presence of mutations in this gene. Among 40 subjects, we identified two mutations, suggesting a prevalence of ~5% in this group. Extrapolating from this result, the prevalence of glucokinase-deficient NIDDM among Americans may be ~1 in 2500. Diabetes 42:937-40, 1993

Within the northwestern islands of the High Arctic, the vegetation and flora of King Christian Island are very representative. Five plant communities were recognized in a moisture gradient from a moss–rush moist meadow with 22 species of vascular plants and 13% cover (total plant cover 93%) to lichen barrens on low ridges with 8 species of vascular plants and 3% cover (total plant cover 24%). Root systems of 30 of the 34 known vascular plant species were examined. Root:shoot ratios (alive) are generally 0.2 to 0.7. Roots are estimated to live 1.5 years in Phippsia algida, 3.4–3.7 years in Alopecurus alpinus and Puccinellia vaginata, and 7–13 years in Luzula nivalis, L. confuse), and Cerastium arcticum. Optimal root growth occurs at 12 to 20 °C but cold field soils (1 to 3 °C) reduce these rates by 90%. Root growth was also reduced by low soil water potentials (< − 14 bars (1 bar = 100 kPa)), conditions seldom encountered in these sites. Limited root growth due to cold soils is combined with the adaptive advantages of small roots to produce small plants and sparse cover in these polar semidesert lands.

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