Stolon

Abstract: A study was conducted to determine the influence of herbage mass under continuous stocking management with sheep on rates of herbage growth (G), senescence (S) and net production of green herbage (NP) in a mixed-species sward of Lolium perenne. Poa annua and Trifolium repens. Plots were maintained in as nearly constant herbage mass as possible at 500, 700, 1000 and 1700 kg organic matter (OM) ha−1 by continuous but variable stocking with sheep for the period May to July inclusive. Estimates of G, S and NP were obtained for each species from repeated measurements over two 2-week periods on individually identified grass tillers or clover stolons. Estimates of species population densities enabled estimates of G. S and NP per unit area to be made. Rates of G were higher and of S were lower for Lolium tillers and Trifolium stolons than for Poa tillers. The laminae of Poa tillers occupied inferior positions in the canopy of the swards maintained at higher herbage masses and were less accessible to the grazing animals, so that Poa tissue was less well utilized. The total population densities of tillers and stolons declined at herbage masses both above and below 700 kg OM ha−1. The rate of G for the three species combined increased with herbage

Abstract: The herbaceous perennial, Fragaria chiloensis, reproduces vegetatively on coastal sand dunes in California by growth of stolons that bear rosettes. Movement of water and photosynthates through stolons integrates water and carbon metabolism of rosettes both before and after they root. New, unrooted rosettes import sufficient water and nitrogen to maintain levels near those of established rosettes; yet support of an unrooted rosette did not decrease growth of a connected, rooted sibling given abundant light, water, and soil nutrients. Under such conditions strings of unrooted rosettes with the associated stolon appeared self-sufficient for carbon; shade and drought induced import of photosynthates. New rosettes produced and maintained a limited root mass upon contact with dry sand, which could increase probability of establishment. Rooting did not induce senescence of stolons. Connection between two established rosettes prevented death by drought and shade, even when neither rosette could have survived singly. Results suggest that physiological integration of connected rosettes may increase total growth of clones of F. chiloensis through sharing of resources among ramets, especially when resource availability is changeable or patchy.

Abstract: (1) The growth forms of genetically identical clones of the perennial herb Glechoma hederacea were compared under three soil nutrient regimes: (i) all ramets were rooted in nutrient-rich sand, (ii) all ramets were rooted in nutrient-deficient sand, (iii) all ramets produced by one primary stolon were rooted in nutrient-rich sand while all ramets produced by the other stolon were rooted in nutrient-deficient sand (split treatment). (2) Clones growing in nutrient-rich sand had short stolon-internodes, copious branching and a rapid accumulation of many large ramets with large leaf-areas. Proportional allocation of dry weight to leaves and petioles was high, whereas allocation to stolons and roots was low. (3) Clones growing in nutrient-poor sand had long stolon-internodes, less frequent branching and a few small ramets with small leaf-areas. Proportional allocation of dry weight to leaves and petioles was low, whereas allocation to stolons and roots was high. (4) Results for the split treatment were intermediate between those of the two singular treatments. There were few significant differences between the half of the split treatment receiving a given treatment and the complete clone receiving the corresponding treatment. Analysis of the split treatment provided no evidence for integration between primary stolons subjected to different nutrient levels. (5) Leaf areas, stolon lengths, number of ramets, stolon branching and dry weight of the primary structures and whole clone increased with clonal age in all treatments. Rate of increase was highest for the nutrient-rich clones, and intermediate in the split treatment clones. (6) The phenotypic plasticity of growth revealed in this experiment may be beneficial since it enables Glechoma hederacea to consolidate its occupation and exploitation of favourable sites (intense foraging), and to pass rapidly through less favourable sites, which may increase the probability of escape into more favourable sites (extensive foraging). The lack of integration between primary stolons may be beneficial in enabling ramets in favourable sites to develop rapidly rather than diverting their accumulated resources to ramets in less favourable areas, which might limit clonal expansion.

Abstract: (1) The growth form of 12-week old clones of Glechoma hederacea grown either under neutral shading (reducing light intensity by 750%), or in full daylight, was compared. All clones were genetically identical. (2) Clones grown under shading displayed a growth form characterised by a small number of slender, unbranched stolons with long internodes, and only a few small ramets. Dry weight per unit length of stolon was low. Proportional allocation of dry weight to roots was low, whereas allocation to petioles was high. Specific leaf area was nearly three times higher in the shaded clones than in the unshaded clones. Mean ramet leaf area was the same for clones in both treatments. (3) The growth form of unshaded clones was characterised by short stolon internodes, frequent stolon branching and many large ramets. The dry weight per unit length of stolon was four times greater than in the shaded clones. Proportional allocation of dry weight to roots was high, whereas allocation to petioles was lower than in the shaded clones. (4) The results of this experiment are compared with published data analysing the response of G. hederacea to different levels of nutrient availability. G. hederacea displays qualitatively similar alterations in growth form in conditions of low light and low nutrient availability. Plasticity in growth form of G. hederacea enables clones to consolidate occupation of favourable sites, through intensive foraging, and to grow through less favourable sites, concentrating resources in extensive foraging which may result in establishment of ramets in more rewarding sites.