Anatomy of the Dicotyledons.
About: This article is published in American Midland Naturalist.The article was published on 1950-11-01. It has received 2511 citations till now.
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TL;DR: An Early Eocene plant assemblage from near the summit of Mt Hotham, Victoria, is described, using a combination of macro- and microfossils, especially cuticles, to suggest climatic conditions similar to those now experienced in regions such as the Atherton Tablelands in Queensland and mid-montane Papua New Guinea.
Abstract: An Early Eocene plant assemblage from near the summit of Mt Hotham, Victoria, is described, using a combination of macro- and microfossils, especially cuticles This is important since no other Australian macrofossil sites from this time, when environmental conditions are believed to have been the warmest of the Cenozoic, have been described in detail The nature of the flora and vegetation supports geological evidence that the site was upland (approximately 800 m above sea level) at this time, with climatic conditions similar to those now experienced in regions such as the Atherton Tablelands in Queensland and mid-montane Papua New Guinea The vegetation was probably a form of rainforest dominated by mesotherm elements, with abundant ferns including Gleicheniaceae and the tree ferns Cnemidaria, Cyathea and Dicksonia Gymnosperms included Araucariaceae (Agathis) and Podocarpaceae (at least Acmopyle and Dacrydium) Angiosperms were diverse in Lauraceae (at least nine species including probably Cryptocarya, Endiandra and Litsea) and Proteaceae (at least nine species including probably Musgravea and Darlingia) Other angiosperms included Cunoniaceae, Gymnostoma (Casuarinaceae), Diospyros-like Ebenaceae, and the vine Cissocarpus (Vitaceae) Nothofagus was rare or absent from the Mt Hotham region at this time, as no macrofossil evidence was found, and pollen percentages were very low
40 citations
TL;DR: This analysis departs from a strict Hennigian approach in permitting some variation within both the outgroup and the ingroup in characters used as synapo- morphies, and evaluates the two hypotheses in light of cladistic principles.
Abstract: The Boraginaceae and Scrophulariales have each been proposed as the closest extant relative of the Lamiales (i.e., Labiatae plus Verbenaceae). Char- acters supporting the two hypotheses are evaluated in light of cladistic principles. Character polarity is determined primarily through outgroup comparison. Because of uncertainty about the identity of the outgroup, separate analyses are conducted in relation to five possible outgroups. No matter which is used, there are more synapomorphies uniting the Lamiales with the Scrophulariales than with the Bora- ginaceae. This analysis departs from a strict Hennigian approach in permitting some variation within both the outgroup and the ingroup in characters used as synapo- morphies. The magnitude of variation in many higher taxa of plants renders im- practical a strict approach requiring consistent character differences. The use of apomorphic tendencies and judicious application of the commonality principle are advocated as means to tentative groupings in such cases. A survey of published phylogenies reveals two opposing viewpoints concerning the closest extant relatives of the Lamiales (i.e., Labiatae plus Verbenaceae; see below). Some authors (Hallier 1912; Dahlgren 1977, 1980; Wagenitz 1977) have asserted that the Scrophulariales is the extant group most closely related to these families, while others have claimed this position for the Boraginaceae s.l. (Wernham 1911; Thorne 1976, 1981; Takhtajan 1980; Cronquist 1981). Proponents of each view stress those characteristics that appear to unite the Labiatae and Verbenaceae with the putatively related group, sometimes attributing to convergence those traits that support the opposing view. It is my intent in this paper to evaluate the two hypotheses in light of cladistic principles. The crux of Hennigian cladistic analysis (Hennig 1966; Bremer and
40 citations
TL;DR: The present study has confirmed the interpretation of some previously recognized features but has also introduced new problems and expanded the understanding of the structure and seasonal changes in the conducting element, the sieve element, and further differentiate this element from the associated nucleate cells.
Abstract: does not appear. First page follows.
Introduction
An intensive investigation of the phloem of Vitis vinifera L., the grapevine, was previously reported in this Journal (Esau, 1948a).3 That study was centered on the development of the tissue, especially with reference
to seasonal changes. It served as a background for the subsequent study of the effects
of Pierce’s disease virus on grapevine (Esau, 1948b). In connection with the earlier study, samples of bark were collected from thirty
species of Vitis, other than V. vinifera, growing in the experimental vineyard of the Department of Viticulture at Davis.
The first part of the present paper reports on a survey of phloem of these species.
After an electron microscope was installed on the Davis campus, the ultrastructure
of phloem tissue became one of the important research projects in the Department of
Botany at Davis. Vitis phloem was included in the studies and a considerable amount of information on this
tissue was obtained during 1960-1962. This information constitutes the major part
of the present paper.
Methodology in submicroscopic research is still new and is changing rapidly. The ultrastructural
data reported here are based on relatively early techniques. Nevertheless, these data
expand the understanding of the structure and seasonal changes in the conducting element,
the sieve element, and further differentiate this element from the associated nucleate
cells. The present study has confirmed the interpretation of some previously recognized
features but has also introduced new problems.
Early ultrastructural investigations on plant material have emphasized meristematic
or relatively undifferentiated parenchyma cells, especially those derived from root
tips (see, for example, (Whaley et al., 1960), and the submicroscopic structure of such cells is relatively well understood. Interpretation
of the fine structure of mature and highly specialized cells must therefore be made
by comparison with the less-differentiated cells. Part of the present paper deals
with the sieve element in the root tip, which was studied against the background of
information on more or less meristematic parenchyma cells of the same parts of the
root. These background observations are reported in full because they help to single
out the specific characteristics of the sieve element.
The literature pertinent to the subject matter is not reviewed under a separate heading.
Certain references are mentioned in connection with individual observations in the
main text, but the comprehensive comparison of data obtained with those reported in
the literature appears only in the discussion. The specific terminology concerning
the phloem tissue is explained in the previous Hilgardia article on Vitis phloem (Esau, 1948a), and that serving for the description of ultrastructural details has been reviewed
by (Esau and Cheadle (1965)).
40 citations
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01 Jan 2010
TL;DR: Biotechnological approaches to aphrodisiac plants of Rajasthan, India and genetic variation in Tunisian date-palm (Phoenix dactylifera L.) are studied.
Abstract: Section A: General biology.- 1 Biodiversity, Biology and conservation of medicinal plants of Thar desert.- Arora J, Goyal S and Ramawat KG.- 2 Potentiality of hydrocarbon yielding plants for future energy and chemicals Kalita D.- 3 Biology and biotechnology advances in Jatropha curcas- A biodiesel plant Reddy MP.- 4 Biology of annual plants in arid and semi-arid desert regions of China Li X.- 5 Soil biology in traditional agroforestry systems of Indian Desert Sundaramoorthy S, Mehar SK, Suthar MS.- 6 Aspects of mycorhizae in desert plants Apple ME.- 7 Anatomical variations in woody plants of arid areas Yang S, Ikiuo F, Jiang Z.- 8 Diversity and conservation in cactus family P. Ortega-Baes et al.- Section B: Reproductive biology.- 9 Reproductive biology of some gum producing Indian desert plants.- Tandon R, Shivanna KR, Mahan Ram HY.-10 Reproductive biology of Cactaceae.- Mandujano MDC, Carillo-Angeles I, Martinez-Peralta C, Golubov J.- 11 Parthenocarpy and seed production in Burseraceae Ramos-Ordonez MF, Marquez-Guzman J, Coro-Arizmendi MD.- Section C: Ecophysiological studies.- 12 Photosynthesis of C 4 desert plants.- Su P.- 13 Polyamines and plant adaptation to saline environment.- Kuznetsov VV, Shevyakova NI.- 14 Ecology of Inland saline plants Kasera PK, Mohammed S.- 15 Ecophysiology of Prosopis species from arid land of Argentina: what do we know about adaptation to stressful environments? Villagra PE, Vilela A, Giordano C, Alvarez JA.- 16 Plant growth inhibitors from mesquite (Prosopis juliflora).- Nakano H.- Section D: Biotechnological studies.- 17 Genetic variation in Tunisian date-palm (Phoenix dactylifera L.).- Rhouma S, Zehdi -Azouzi S,Dakhlaoui-Dkhil S, Ould Mohamed Salem AOB, Othmani A, Cherif E, Marakachi M, Trifi M .- 18 Biology and muliplication of Prosopis species grown in.- Thar Desert.- Raj Bhansali R.- 19 Biotechnology advances in jojoba (Simmondsia chinensis).- Reddy MP, Chikara J.- 20 DatePalm Cultivation in Changing scenario of Indian Arid Zone: Challenges and Prospects.- Raj Bhansali R.- 21 Runoff-rainwater for sustainable desert farming.- Luttge U.- 22 Biotechnological approaches to aphrodisiac plants of Rajasthan, India .- Jain N, Goyal S, Ramawat KG.
40 citations
TL;DR: The assumed “intermediate” genus Paraprotium is shown to be an unnatural assemblage and is here merged withProtium and this revised concept of generic limits in the Neotropical Protieae and Canarieae leads to the following new combinations.
Abstract: Trattinnickia is closely related toDacryodes and is transferred to the tribe Canarieae. Additional characters are proposed to supplement the weak characters that traditionally have been used to separateCrepidospermum andTetragastris fromProtium. The assumed “intermediate” genusParaprotium is shown to be an unnatural assemblage and is here merged withProtium. This revised concept of generic limits in the Neotropical Protieae and Canarieae leads to the following new combinations:Tetragastris occhionii (Rizzini) Daly,Protium pilosum (Cuatrec.) Daly,Protium nitidifolium (Cuatrec.) Daly,Protium vestitum (Cuatrec.) Daly, andDacryodes cuspidata (Cuatrec.) Daly. A key to the Neotropical genera of Burseraceae is provided.
40 citations