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: In this article, the authors reported qualitative and quantitative wood features for 38 species representing 22 genera of Acanthaceae, including the scandent genera Mendoncia and Thunbergia.
Abstract: Qualitative and quantitative wood features are reported for 38 species representing 22 genera, including the scandent genera Mendoncia and Thunbergia. Woods of Acanthaceae are characterized by relatively narrow vessels with simple perforation plates and alternate lateral wall pining, septate libriform fibers, scanty vasicentric axial parenchyma, rays both multiseriate and uniseriate, erect ray cells abundant in rays (some species rayless or near-rayless), numerous small crystals or cystoliths in ray cells in a few genera (first documented reports of both characters in woods of Acanthaceae), and nonstoried structure. This constellation of features is very closely matched by woods of Gesneriaceae, Scrophulariaceae, Pedaliaceae, Martyniaceae, Bignoniaceae, and Myoporaceae (families listed in order ofdecreasing resemblance). Narrowness ofvessels in tropical Acanthaceae appears related to understory ecology. A few species in warm and seasonally dry areas have narrow, short vessel elements numerous per unit transection. Vasicentric tracheids occur in two nonscandent genera in dry areas. Vessel grouping is roughly proportional to dryness of habitat. Thunbergia alata, T. laurifolia, and all collections of Mendoncia have interxylary phloem (first report for Mendoncia). That feature, plus presence of occasional acicular crystals in rays and axial parenchyma and presence of large gelatinous fibers in phloem ally Mendoncia closely with Thunbergia, and Mendonciaceae is not justified for this and other reasons Species of Thunbergia differ among themselves, and T. erecta and T. holstii resemble shrubby Acanthaceae more than they do Mendoncia in wood features. Thunbergia thus should not be segregated from Acanthaceae.
26 citations
TL;DR: It is concluded that the relatively minor reductions in midday Ψ sw may be insufficient to entirely explain PPD symptoms and should not be considered as a cause for concern.
26 citations
TL;DR: Correlations among comparative observations on pollen grains, stomata and stem anatomy suggest that the Labiatae family comprises two main groups, which were hinted at by Bentham but completely obscured by the currently fashionable classification of Briquet.
Abstract: Summary
Correlations among comparative observations on pollen grains, stomata and stem anatomy tor 125 genera of Labiatae suggest that the family comprises two main groups This situation was hinted at by Bentham, but is completely obscured by the currently fashionable classification of Briquet The rust fungus Puccinia menthae Pers exhibits a very marked preference for members of one group (seventy recorded host species) over the other (only one host species)
26 citations
TL;DR: Investigating the fossil record from the Neogene of the Central Andean Plateau and documenting the earliest evidence of a puna-like ecosystem in the Pliocene and a montane ecosystem without modern analogs in the Miocene suggest wetter than modern precipitation conditions during the pliocene.
Abstract: Andean uplift played a fundamental role in shaping South American climate and species distribution, but the relationship between the rise of the Andes, plant composition, and local climatic evolution is poorly known. We investigated the fossil record (pollen, leaves, and wood) from the Neogene of the Central Andean Plateau and documented the earliest evidence of a puna-like ecosystem in the Pliocene and a montane ecosystem without modern analogs in the Miocene. In contrast to regional climate model simulations, our climate inferences based on fossil data suggest wetter than modern precipitation conditions during the Pliocene, when the area was near modern elevations, and even wetter conditions during the Miocene, when the cordillera was around ~1700 meters above sea level. Our empirical data highlight the importance of the plant fossil record in studying past, present, and future climates and underscore the dynamic nature of high elevation ecosystems.
26 citations
01 Jan 1966
TL;DR: A. P. De Candolle as discussed by the authors put forward two postulates: (i) Plant taxonomy will be the most useful guide to man in his search for new industrial and medicinal plants; (ii) Chemical chara cteristics of plants will be most valuable to plant taxonomy in the future.
Abstract: Chemical plant taxonomy or chemotaxonomy of plants may be defined as a sciertific investigation of the potentialities of chemical characters for the study of problems of plant taxonomy and plant phylogeny. Plant taxonomy is the science of delimiting, describing and naming appropriately taxat and arranging them in a natural system of plants. Principles of chemotaxonomy were elaborated in the past century by A. P. De Candolle1 and by Greshoff2. De Candolle put forward two postulates: (i) Plant taxonomy will be the most useful guide to man in his search for new industrial and medicinal plants; (ii) Chemical chara cteristics of plants will be most valuable to plant taxonomy in the future. While the first postulate of De Candolle proved to be extremely fruitful and has been applied repeatedly when new sources of promising plant constituents are to be detected, his second postulate came to be accepted very slowly. Researchers like Rochleder3, Greshoff4, Rosenthaler5, Baker and Smith6, Wheldale7, Iwanow8, Cohn9, Molisch1°, McNair'1 and Weevers'2 were enthusiastic but rather isolated workers in the field of chemotaxonomy. However, the fact that the first postulate of De Candohle was applied very successfully by generations of phytochemists forms an indirect proof of the validity of his second postulate. Some examples may serve to illustrate just the services plant taxonomy renders to chemists interested in distinct types of plant constituents. When the pharmaceutical industry became interested in plant steroids as starting materials for hormone synthesis, the search for suitable sources was essentially guided by taxonomic concepts. The genus Strophanthus was investigated first for cardenolides and its species proved, without exception, to accumulate members of this category of phytoconstituents. Thousands of species were screened for steroidal sapogenins and in the taxa already known to contain them, i.e. in Agavaceae, Dioscoreaceae and Liliaceae, by far the highest frequency of occurrence was observed. In recent years the pregnane-derived alkaloids have begun to attract attention. Such alkaloid-like substances had been known for several years to be present in the apocynaceous genus Holarrhena. In this instance too, an alliance of genera included by taxonomists in the plant family Apocynaceae proved to be most promising for exploration. Very recently
26 citations