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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: The characteristics and stratigraphic position of this leaf type support the hypothesis that modern tribes and possibly genera of Rhamnaceae had evolved by the Middle Eocene.
Abstract: Leaf compressions, previously assigned to Rhamnus marginatus Lesquereux, were collected from the Middle Eocene Claiborne Formation of western Kentucky and Tennessee. The leaf architecture and cuticular features of over 40 compressions were carefully examined and compared to those of many extant species of Rhamnaceae and related families as well as fossil specimens previously assigned to this taxon. This leaf type appears to belong to the Rhamnaceae, however, it conforms more closely to species of several genera in the tribe Zizypheae than to those of Rhamnus or other genera in the tribe Rhamneae. Confident assignment to any specific genus within this complex of genera cannot be made on the basis of leaf characteristics alone and would require discovery and analysis of additional vegetative and reproductive organs. Because this fossil leaf form cannot be confidently assigned to any modern genus and earlier classifications appear to be improper, this leaf type has been reassigned to the taxon Berhamniphyllum claibornense gen. et sp. nov. The transfer of this leaf form at the tribe level reaffirms the need for close examination of taxonomic determinations made by early workers. The characteristics and stratigraphic position of this leaf type support the hypothesis that modern tribes and possibly genera of Rhamnaceae had evolved by the Middle Eocene.

28 citations

Journal Article
TL;DR: In this article, the authors present morphological, anatomical and ecological features of S. limbata C.A. Meyer and S. palaestina Bentham as well as micromorphological characteristics of their pollen grains and nutlets.
Abstract: Morphological characteristics of stems, leaves, bracts, calyces and corollas are taxonomically discriminating characters in Salvia. In this paper we present morphological, anatomical and ecological features of S. limbata C.A. Meyer and S. palaestina Bentham as well as micromorphological characteristics of their pollen grains and nutlets using scanning electron microscopy. Anatomical characters such as size of cortex and vascular tissue, number of palisade parenchyma rows and vascular bundles are found to be important species specific characters. Pollen grains in the species are different in shape and size, but they look similar in their exine sculpturing; shape, size and ornamentation of nutlets are found to be different. The two investigated Salvia species grow on clayey-loamy and loamy soils, with pH 7.6–7.9, with 0.4–2.1% of organic matter, 0.006–0.026% of total salt content, 4.2–21.0 mg kg –1 phosphorus and 87.0–445.8 mg kg –1 potassium.

28 citations

Journal ArticleDOI
TL;DR: The re-circumscribed Aquilarioideae together with Thymelaeoideae and Synandrodaphnoideae are shown to form a monophyletic group.
Abstract: Pollen morphology of the four subfamilies of Thymelaeaceae sensu Domke (1934) was examined using LM, SEM and TEM. The variation of the exine architecture allows to distinguish four pollen types and three subtypes. Distribution of pollen types proves to be widely correlated with the occurrence of characters from wood anatomy and flower morphology. If pollen types are connected with subfamilies sensu Domke (1934), Gonystyloideae, Thymelaeoideae and Synandrodaphnoideae are stenopalynous, whereas Aquilarioideae are eurypalynous. Based on pollen morphology as well as on other characters it is evident that Aquilarioideae are not monophyletic. Its genera Aquilaria and Gyrinops are more closely related to Thymelaeoideae and Synandrodaphnoideae than to other genera of Aquilarioideae sensu Domke (1934). The remaining genera of Aquilarioideae Deltaria, Solmsia and Lethedon are most similar to Gonystyloideae and therefore are included in this subfamily, as it was suggested by Airy Shaw (1979). Furthermore, palynological and other characters favour the transfer of Octolepis from Aquilarioideae to Gonystyloideae. The re-circumscribed Aquilarioideae together with Thymelaeoideae and Synandrodaphnoideae are shown to form a monophyletic group.

28 citations

Journal ArticleDOI
TL;DR: The anatomy of dermal, fundamental and vascular systems, aiming to find diagnostic characters for the genera and species of Arrojadoa, Stephanocereus and Brasilicereus are described.
Abstract: (Anatomy of Brazilian Cereeae (subfamily Cactoideae, Cactaceae): Arrojadoa Britton & Rose, Stephanocereus A. Berger wâBrasilicereus Backeberg). Arrojadoa, Stephanocereus and Brasilicereus are endemic Brazilian Cereeae, occurring along the Espinhaco Range, in the campos rupestres, cerrados and caatingas, from northern Minas Gerais to southern Bahia. The genera are columnar, erect to semi-erect cacti, except for one species, A bahiensis, which is globose. This study describes the anatomy of dermal, fundamental and vascular systems, aiming to find diagnostic characters for the genera and species. Basal portions of stems were sectioned transversely and longitudinally, and stained with Astrablue and Safranin. The species share a uniseriate epidermis, with thick cuticle; well developed collenchymatic hypodermis, containing prismatic crystals; cortex with numerous mucilage cells, druses and vascular bundles; outside cortex as a palisade parenchyma; periderm composed of lignified cork cells alternating with suberized cells; pheloderm consisting of a few layers of thin-walled cells; phloem composed of solitary or multiple of two to three sieve tube elements, companion cells, axial and radial parenchyma; secondary xylem with solitary to multiple vessels, with simple perforation plates and alternate bordered to semi-bordered pits; axial parenchyma scanty vasicentric to incomplete; libriform septate fibres; large rays. Unlignified parenchyma is seen in the secondary xylem, varying from a few cells to bands among axial and radial elements. The following are considered diagnostic characters: the shape of lignified phellem cells, cubic to radially elongate, which individualizes S. leucostele; an underdeveloped hypodermis and the occurrence of sclereids in the cortex are exclusive to Brasilicereus markgrqfii.

28 citations

Journal ArticleDOI
TL;DR: The extremely well-developed apical septum in the eusyncarpous gynoecium of Rhopalocarpus suggests that the gynoterminal style present in this genus has been secondarily derived from an ancestor with a fully syncarpous, basistylous gynaecium, as in Dialyceras.

28 citations