Variation In Leaf Morphology Research Articles

Variations in the shallow water form of Potamogeton richardsonii induced by some environmental factors

SUMMARY. Populations of Potamogeton richardsonii in Sparrow Lake, Ontario, vary greatly in leaf dimensions and internode length. Leaf length/breadth (L/B) ratio is increased by low irradiance, significantly at 4% daylight and, in a contrary fashion, by ontogenetic drift at high irradiances of shallow water. L/B ratio was not correlated with substrate. These findings suggest that this ratio is of doubtful value taxonomically or as an integrator, as specific leaf area is confirmed to be, of factors like photosynthetically active radiation (PAR). Longest internodes belong to plants from deep(1.8 m) water, and, in a summer‐grown high‐density population, internode length decreases logarithmically as depth lessens; both observations implicate PAR and ageing. Relative to undisturbed, shallow‐water shoots, young transplants in full daylight elongate almost twice as fast because of the production of more, and longer, internodes. Young shoots in 12% daylight lengthen even more rapidly than those in full daylight (and four times faster than undisturbed shoots) in the same period because of quicker elongation of the same number of internodes. At ambient summer temperatures, this rate of elongation is inversely related to PAR. Experimental and seasonal field data indicate that maximal internode extension occurs on young shoots in very low irradiances at temperatures of 9–15°C; in nature, effects of increasing water temperatures are depressed by increasing irradiances and ageing until minimal extension takes place in old shoots at mid‐ to late‐summer temperatures and in high irradiances. In tanks (40 m3) in full daylight, nutrients limit growth of plants on sand before they limit growth on clay (with marl intermediate) whereas, at 12% daylight, light limits growth on sand before soil nutrients do. The leaf area index on silty sand on an exposed shore was 0.4 at 0.5 m depth, in contrast to a cultured population where it was 4.0 in silty loam at the same depth. Thus, while it has not been possible to explain some variations in leaf morphology of P. richardsonii in environmental terms, the differential effects of ontogeny, PAR and temperature on shoot growth have been assessed, along with overall effects of light and nutrients on biomass and of shelter on leaf area index.

The Problem of Leaf Morphology and Evolution in the Monocotyledons

A review of the previous literature on the morphology and evolution of monocotyledonous leaves reveals a number of interpretive controversies and contradictions. The phyllode theory, which has been the prevailing interpretation of the origin and evolution of monocotyledonous leaves, is evaluated and is shown to have been biased by a preoccupation with temperate monocotyledons and the exclusive study of mature leaf morphology and vascular anatomy. Recent investigations of comparative development have provided a broader basis for the evaluation of structural relationships of leaves in the monocotyledons and dicotyledons and have served to eliminate some of the interpretive inconsistencies that were based on the study of vascular anatomy only. The most controversial leaf type in the monocotyledons has been the unifacial (radially symmetrical) leaf found in a number of divergent families. Contrary to the original Phyllode theory of the Candolle (1827) and Arber (1918), developmental comparison of unifacial appendages of monocotyledons with rachis leaves of Umbelliferae suggests that the terete leaf axis of the former is not simply an elaborated petiole but is positionally equivalent to the laminar region of a dicotyledonous leaf. Instead of being expanded in surface by marginal growth, the unifacial moncotyledonous leaf is thickened developmentally and hence has become nearly radial in summetry. Thus the original phyllode concept of the loss of the blade retion and the expansion and assumption of its function by the petiole no longer seems valid for monocotyledonous leaves. In addition, comparative developmental studies, as well as the analysis of serial changes in leaf morphology, have confirmed that where dorsiventral, laminar leaves are developed in the monocotyledons, they are developmental elaborations of the basal, meristem-encircling part of the leaf primordium, and the distal upper leaf zone remains rudimentary. Therefore, blade regions of such dorsiventral appendages are not homologous with those of dicotyledons because they have a different developmental origin; laminae of dicotyledons are derived from the upper leaf zone. It is suggested that the basic construction of monocotyledonous leaves consists of two regions: (1) a distal unifacial upper sector; and (2) a proximal bifacial sheath; variations in leaf morphology in a range of monocotyledonous taxa are therefore due to reciprocal elaboration, or suppression of these two sectors, or both. It is emphasized, however, that before any model of this sort can be extended to the monocotyledons as a whole, it must be evaluated rigorously in the broadest range of representatives from each major family.

VARIATION IN GENTIAN A VERNA L.

SummaryThe British populations of Gentiana verna are clearly distinguishable morphologically into two groups by both calyx and leaf characters. These groups are coincident with the geographical areas of the species, Teesdale in north England and Galway Bay in west Ireland. On the Continent, populations from the Alps and Pyrénées are indistinguishable in calyx characters, but are significantly different from English and Irish populations. Leaf length and length/ breadth ratio are correlated and the leaf length/breadth ratio of the Continental populations is clinally correlated with their altitude. Leaf characters of British populations are similar to those Continental populations from higher altitudes, those from Teesdale being indistinguishable from those at the highest altitudes. It is considered that these differences may either be the result of random drift or genecological differentiation. The possibility of variation in leaf morphology being related to heat transfer properties is discussed.

A study of concept development and communication abilities in young children using variations in leaf morphology

A study of concept development and communication abilities in young children using variations in leaf morphology

Variation of morphological and protein pattern of cassava (Manihot esculenta) varieties of Adira1 and Cabak makao in Ngawi, East Java

Abstract. Tribadi, Suranto, Sajidan. 2009. Variation of morphological and protein pattern of cassava (Manihot esculenta) varieties of Adira1 and Cabak makao in Ngawi, East Java. Nusantara Bioscience 2: 14-22. This research is intended to find out the morphological and anatomical variation as well as the protein band pattern of cassava (Manihot esculenta Crantz) widely spread in three different areas of height. The sample collecting is done using simple random sampling in the three different areas of height that is 50, 300, 1000 meters asl in Ngawi District, East Java while the analysis of protein band pattern is done using SDS-PAGE. The result of the research of morphology and anatomy is analyzed descriptively and presented in the form of tables, histograms, and figures. The analysis of protein band pattern is done using quantitative and qualitative analysis that is based on the appearance or not the gel band pattern by counting the molecular weights based on code marker S 8445 and qualitative method based on the quality of the band formed. The band pattern formed is istimated and presented in the form of zimogram. The result of the research shows that the height of the cultivating site very much influences toward variations of root, stem and leaf morphology. The longest root is at 50-meter heights asl (Cabak makao local variety, the widest stem diameter is at 50 meters asl (Cabak makao local variety) the longest leaf and branch is at 300 meters asl (Cabak makao local variety) and 1000 meters asl (Cabak makao local variety). There is no difference of anatomy in the root, stem, and leaf and no difference of protein band pattern either in Adira1 or Cabak makao local variety.

Variation of Quercus Muehlenbergii in Kansas

K. YOKOYAMA and R. L. McGREGOR University of Kansas, Lawrence Colonies of Quercus muehlenbergii Engelm. in eastern Kansas exhibit a wide range of variation in external leaf morphology. Since leaf characters are important, though variable, in species determination of oaks, and have been used for subspecific segregations, it was decided to study the range of variation to be found in colonies of this oak. Its distribution in