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Journal ArticleDOI

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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Journal ArticleDOI
TL;DR: This review investigates patterns of growth form diversification in Piperales, an early-diverging lineage and the most morphologically diverse clade among magnoliids, as well as the biomechanical significance of developmental characters, such the organization, loss, and gain of woodiness.
Abstract: A striking feature of early angiosperm lineages is the variety of life forms and growth forms, which ranges from herbs, aquatic herbs, climbers, and epiphytes to woody shrubs and trees. This morphological and anatomical diversity is arguably one of the factors explaining how angiosperms dominate many ecosystems worldwide. However, just how such a wide spectrum of growth forms has evolved in angiosperms remains unclear. In this review, we investigate patterns of growth form diversification in Piperales, an early-diverging lineage (with stem age estimated at 201–128 Myr ago) and the most morphologically diverse clade among magnoliids. We outline patterns of growth form diversity and architecture as well as the biomechanical significance of developmental characters, such the organization, loss, and gain of woodiness. Asaroideae and Saururaceae are terrestrial as well as semiaquatic to aquatic herbaceous perennials bearing rhizomes. The Aristolochioideae and Piperaceae show higher levels of growth form divers...

60 citations


Cites background from "Anatomy of the Dicotyledons."

  • ...Whatever the ecological conditions and putative habit of the ancestral angiosperm, the early-diverging lineages of extant angiosperms show a diversity of forms ranging from woody trees and shrubs (e.g., Amborellales, Austrobailayales, Chloranthales), woody vines (Austrobailayales, Magnoliales, Laurales, Piperales), and herbs with limited woody development (Chloranthales, Piperales) to herbs lacking wood and often linked to aquatic life forms (Nymphaeales; Feild and Arens 2005; Spicer and Groover 2010; fig....

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  • ...While some angiosperm taxa truly lack a secondary vascular cambium (e.g., monocots, Nymphaeales; Metcalfe and Chalk 1979; Carlquist and Schneider 2009; Carlquist et al. 2009), many angiosperms described as herbaceous do in fact show cambial activity, which may be limited to vascular bundles of the primary body....

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  • ...While some angiosperm taxa truly lack a secondary vascular cambium (e.g., monocots, Nymphaeales; Metcalfe and Chalk 1979; Carlquist and Schneider 2009; Carlquist et al. 2009), many angiosperms described as herbaceous do in fact show cambial activity, which may be limited to vascular bundles of the…...

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Journal ArticleDOI
TL;DR: The orderCentrospermae (Caryophyllales, Chenopodiales) as treated in A. Englers Syllabus, 12th edition (1964), is compared with several other modern and older systems with the result that no less than 11–13 families are considered to be centrospermous in the strict sense.
Abstract: The orderCentrospermae (Caryophyllales, Chenopodiales) as treated inA. Englers Syllabus, 12th edition (1964), is compared with several other modern and older systems with the result that no less than 11–13 (and more) families are considered to be centrospermous in the strict sense; to these may be added thePolygonales and, doubtfully, thePlumbaginales andBatidales. As indicated by their name “Centrospermae” their main character is the central or basal placentation in combination with campylotropy (or amphitropy) of the ovules, seeds with perisperm, and coiled or curved embryos in peripheral position. Other outstanding features are found in the embryology; the ovules are bitegmic-crassinucellate, a nucellar cap is present, as well as an endostome and air spaces; the pollen is trinucleate. Anomalous secondary thickening in stems and roots often occurs. The pollen morphology, specific P-type sieve-element plastids, and the presence or absence of betalains are also important characters. Other floral features, especially the structure of the gynoecium, the androecium, the perianth and the receptacle, as well as the morphology of the inflorescences are of taxonomic importance. The putative relationships of theCaryophyllidae can perhaps best be resolved on the basis of more detailed morphological investigations (e.g. the so-called apocarpy, the development of the androecium, the pollen morphology, chromosome numbers, etc.).

60 citations

Journal ArticleDOI
TL;DR: O jatoba-do-cerrado apresenta nectarios extraflorais (NEFs), os quais sao descritos pela primeira vez no genero, y as celulas apresentam citoplasma denso, nucleo volumoso, mitocondrias, plastidios com sistema ofente pouco desenvolvido.
Abstract: O jatoba-do-cerrado (Hymenaea stigonocarpa Mart. ex Hayne) apresenta nectarios extraflorais (NEFs), os quais sao descritos pela primeira vez no genero. Neste trabalho foram estudadas a distribuicao, ontogenese, estrutura e ultra-estrutura dos nectarios extraflorais (NEFs). Amostras de folhas em varias fases de desenvolvimento foram coletadas, fixadas e processadas para estudos em microscopia de luz e eletronica de transmissao e varredura, segundo tecnicas convencionais. Testes histoquimicos foram empregados para determinar a natureza quimica da secrecao. Os NEFs estao distribuidos por todo o limbo, sendo mais concentrados nos tercos basal e medio de cada foliolo. Estes nectarios sao embutidos no mesofilo, apresentam tecido secretor envolvido por uma endoderme e sao vascularizados por xilema e floema. A atividade secretora dos NEFs e limitada a fase juvenil da folha. Nas folhas mais velhas, os NEFs tornam-se nao funcionais. O tecido secretor dos NEFs e formado a partir da protoderme, enquanto a endoderme tem origem no meristema fundamental. No tecido secretor de nectarios funcionais as celulas apresentam citoplasma denso, nucleo volumoso, mitocondrias, plastidios com sistema de membranas pouco desenvolvido, gotas de oleo dispersas no citosol, dictiossomos e segmentos de reticulo endoplasmatico liso. A secrecao e liberada por meio de rupturas cuticulares e apresenta polissacarideos e lipidios.

60 citations

Journal ArticleDOI
TL;DR: Shukla et al. as discussed by the authors described tropical African taxa from the upper Cenozoic sediments of western India and their palaeoecological and phytogeographical significance.
Abstract: Shukla, A., Mehrotra, R.C. & Guleria, J.S. iFirst article. African elements (fossil woods) from the upper Cenozoic sediments of western India and their palaeoecological and phytogeographical significance. Alcheringa, 1–20. ISSN 0311-5518. Fossil woods resembling tropical African taxa are described from late Neogene–Pleistocene sediments of western India. They resemble the extant representatives of Baphia Afzel., Brachystegia Benth., Erythrophleum Afzel. (Fabaceae), Entandrophragma C. DC., Khaya A. Juss. (Meliaceae) and Milicia Sim (Moraceae). The discovery of these taxa indicates the invasion of African elements into the Indian subcontinent during the Plio-Pleistocene and palaeogeographic connections between the two continents. All these genera include both evergreen and deciduous representatives and grow mainly in the tropical forests of Africa. On this basis, the presence of semi-evergreen to deciduous forest is inferred in western India during the Neogene in contrast to the semi-arid to arid climate wi...

60 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated the use of needle litter of Pinus pinaster Ait in manufacturing three-layer particleboard and found that needle litter usage decreased the mechanical properties of the particleboard.

60 citations