American Journal of Botany
Công bố khoa học tiêu biểu
Sắp xếp:
Elevated temperatures increase leaf senescence and root secondary metabolite concentrations in the understory herb <i>Panax quinquefolius</i> (Araliaceae) The response of understory species to elevated temperatures is not well understood but is important because these plants are highly sensitive to their growth conditions. Three‐year‐old plants of Panax quinquefolius , an understory herb endemic to the eastern deciduous forests of North America, were grown in a greenhouse at 25/20°C (day/night) or 30/25°C for one growing season and analyzed each month. Plants grown at high temperatures had an early onset of leaf senescence and therefore accumulated less carbon. From May to July, P. quinquefolius grown at high temperatures had decreased photosynthesis (52%), stomatal conductance (60%), and root and total biomass (33% and 28%, respectively) compared to plants grown at low temperatures. As P. quinquefolius prepared to overwinter, plants grown at high temperatures had less root biomass (53%) than plants in low temperatures. The amount of storage‐root ginsenosides was unaffected by temperature, and differences in storage root size may explain why plants grown at high temperatures had greater concentrations of storage root ginsenosides (49%) than plants grown at low temperatures. Panax quinquefolius is clearly sensitive to a 5°C increase in temperature, and therefore other understory species may be negatively impacted by future increases in global temperature.
American Journal of Botany - Tập 94 Số 5 - Trang 819-826 - 2007
CLASSIFICATION OF THE ARCHITECTURE OF DICOTYLEDONOUS LEAVES A classification of the architectural features of dicot leaves—i.e., the placement and form of those elements constituting the outward expression of leaf structure, including shape, marginal configuration, venation, and gland position—has been developed as the result of an extensive survey of both living and fossil leaves. This system partially incorporates modifications of two earlier classifications: that of Turrill for leaf shape and that of Von Ettingshausen for venation pattern. After categorization of such features as shape of the whole leaf and of the apex and base, leaves are separated into a number of classes depending on the course of their principal venation. Identification of order of venation, which is fundamental to the application of the classification, is determined by size of a vein at its point of origin and to a lesser extent by its behavior in relation to that of other orders. The classification concludes by describing features of the areoles, i.e., the smallest areas of leaf tissue surrounded by veins which form a contiguous field over most of the leaf. Because most taxa of dicots possess consistent patterns of leaf architecture, this rigorous method of describing the features of leaves is of immediate usefulness in both modern and fossil taxonomic studies. In addition, as a result of this method, it is anticipated that leaves will play an increasingly important part in phylogenetic and ecological studies.
American Journal of Botany - Tập 60 Số 1 - Trang 17-33 - 1973
Nutritional Requirements of Fraxinus Callus Cultures
American Journal of Botany - Tập 53 Số 3 - Trang 263 - 1966
Reconstructions of Archaeopteris, and Further Consideration of its Phylogenetic Position
American Journal of Botany - Tập 49 Số 4 - Trang 373 - 1962
Cuticular Analysis of Eocene Leaves of Ocotea obtusifolia
American Journal of Botany - Tập 50 Số 1 - Trang 1 - 1963
Calamocarpon Insignis, a New Genus of Heterosporous, Petrified Calamitean Cones from the American Carboniferous
American Journal of Botany - Tập 50 Số 5 - Trang 469 - 1963
On the Occurrence of Psilophyton princeps in the Early Upper Devonian of New York
American Journal of Botany - Tập 48 Số 6 - Trang 473 - 1961
Lepidophlois -- And Ontogeny in Arborescent Lycopods
American Journal of Botany - Tập 45 Số 7 - Trang 552 - 1958
A Calamitean Shoot Apex from the Pennsylvanian of Iowa
American Journal of Botany - Tập 48 Số 9 - Trang 811 - 1961
Archaeopteris macilenta, Anatomy and Morphology of Its Frond
American Journal of Botany - Tập 53 Số 7 - Trang 719 - 1966
Tổng số: 48
- 1
- 2
- 3
- 4
- 5