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: The degree of relationship between these two habitally very distinct species is determined in the light of a comparative anatomical investigation; their position within the family Onagraceae is investigated; and a description of the ontogeny of their bizarre fruiting structures is provided.
Abstract: The unique fruiting structures of the closely related, principally Mexican, monotypic genera Gongylocarpws and Burragea (Onagraceae) compelled a detailed anatomical and cytological investigation of these plants which led to the conclusion that they should be included in a single genus, Gongylocarpus. Gongylocarpus fruticulosus (Burragea), endemic to two adjacent islands off the west coast of Baja California, is divided into two subspecies, subsp. fruticulosus and subsp. glaber. The vegetative and floral anatomy, including wood anatomy, of both species is described. The fruits of these two species grow into the stem by meristematic activity during the course of ontogeny, the ovaries in the mature flower being superficial and sessile in the leaf axil. There is no pedicel associated with the flower, but only a branch gap. Meristematic tissue at the base of the locules divides rapidly at a relatively late ontogenetic stage, the ovaries growing downward into the stem and crushing the pith. The mature, heavily sclerenchymatous fruits are located wholly within the stem, and in G. fruticulosu.s they are aggregated into long chains. Both species have a gametic chromosome number of n = 11, a characteristic otherwise unknown in the tribe Onagreae but shared with other generalized groups in the family. Taken together with other features, this suggests a primitive position within the tribe for Gongylocarpus. GONGYL0CARPuS (0NAGRAcEAR) is a principally Mexican genus of two very distinctive species characterized by a unique fruiting structure. In both, as will be shown in this article, the mature capsules become deeply imbedded in the pith of the stems on which they are borne. One of these species, G. rubricaulis Schlecht. & Cham. (Fig. 3), is a weedy annual with small white flowers, widespread in mainland Mexico and adjacent Guatemala, from ca. 1200—2300 m elevation (Fig. 1). The other, G. fruticulosus (Benth.) T. S. Brandegee (Fig. 2), is a low shrub with large purple flowers, entirely confined to two adjacent islands in Bahia Magdalena, Baja California, where it occurs near sea level (Fig. 1). The latter was segregated as the genus Bur ragea by Smith and Rose in 1913, and this segre gate genus has subsequently been accepted as distinct. The present study was undertaken to determine the degree of relationship between these two habitally very distinct species, particu larly in the light of a comparative anatomical investigation; to investigate their position within the family Onagraceae; and to provide an ade quate description of the ontogeny of their bizarre fruiting structures. ‘Received for publication May 25, 1965. This work was supported in part by National Science Foundation grants GB—14 and GB—4161 (Raven). The authors are grateful to Dr. Reid Moran for his excellent anatomical and cytological material of Gongylocarpus fruticulosus (Burragea), and especially to Mr. and Mrs. Richard Dwyer, owners of the research vessel Gringa, for making Dr. Moran’s trip possible; and to Mr. D. E. Breedlove (supported in the field by N.S.F. grant GS—383) for his fine material and observations of C. rubricaulis. The genus Gongylocarpus first came to the attention of the botanical world through collec tions of the weedy annual G. rubricaulis (Fig. 3) made by Schiede and Deppe from “eultis et incultis circa Jalapam” (i. e., near Jalapa, Vera Cruz). This material was made the basis of a new genus and species by Schlechtendal and Chamisso in 1830. The species is so distinct and uniform that it has never been placed in any other genus, described under any other name, or subdivided taxonomically. Its flowers open early in the morning and the short white petals are fugacious; collections made in the middle of the day or in the afternoon often lack them com pletely. The anthers deposit pollen directly on the globose stigma soon after the flowers open, although the stigma may ultimately be held above the anthers. A full complement of seed is set following self-pollination. We have not seen insects at the flowers of the two populations studied in Chiapas (cited below), nor on plants cultivated in San Cristobal las Casas, Chiapas, within the native range. This predominant autog amy may help to account for its uniformity over its rather wide range (Fig. 1). Gongylocarpus rubricaulis very often occurs as a weed in corn fields, where its lax reddish stems may be con spicuous locally; sometimes it is found on rocky slopes, particularly in disturbed ground, and sometimes in moist places. Although widespread, it is not often collected and is rather sporadic and local in occurrence. The second species of the genus, G. fruticulosus (Fig. 2), was described by Bentham (1844, p. 15) as an aberrant species of Gaura. Bentham
17 citations
TL;DR: In this article, the potential of fossil wood and charcoal from browncoal deposits as sources of reliable paleoenvironmental information is explored with material from the Lower Rhine Embayment (Germany).
Abstract: The potential of fossil wood and charcoal from browncoal deposits as sources of reliable paleoenvironmental information is explored with material from the Lower Rhine Embayment (Germany). The presence of charcoalified material demonstrates proof of natural wildfires in Tertiary mire environments, most probably during, or after periods of increased drainage and drying of surface vegetation and litter. The results presented suggest that sampling from charcoal layers may provide a more statistically reliable data set for study of such environments. Inclusion of taxa recovered from charcoal layers might compensate for the taphonomic and preservational bias of Tertiary lignitic floras based solely on the collection of lignitic wood. These data confirm the hypothesis that, during certain intervals of the Miocene, both monocotyledonous and dicotyledonous angiosperms might have dominated or represented significant portions of the peat-forming vegetation. The importance of palms and shrubby woody taxa, such as ‘Cyrilla’, is particularly striking from new evidence of charcoalified remains. In addition, certain wood anatomical features observed from well preserved lignitic wood and charcoal may be used as indicators of environmentally modulated growth: (1) clear growth rings testify to the existence of a seasonal climate; (2) wide variations in growth ring characters indicate variable environmental conditions; and (3) high incidence of dicotyledonous taxa, with abundant small vessels and scalariform perforation plates, is interpreted as evidence of a mesic environment.
17 citations
Cites background from "Anatomy of the Dicotyledons."
...Identification involved comparison of fossil material with extant wood anatomy atlases (Phillips, 1949; Metcalfe and Chalk, 1950, 1983; Greguss, 1955, 1959; Schweingruber, 1990, Ilic, 1991; amongst others), and with reference collections of extant species (thin sections)....
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01 Feb 1969
TL;DR: From a comparison with other Convolvulaceous genera like Bonamia, Ipomoea, Maripa, Neuropeltis, and Prevostea¹ it appears that nearest to Dicranostyles in general appearance as well as in anatomical structure is the genus MaripA.
Abstract: The anatomy of the mature wood of three species of the South American genus of woody climbers Dicranostyles Bth. is described and compared with that of the secondary wood of other genera of the Convolvulaceae. The stems are characterized by the occurrence of concentric rings of included phloem tissue. In most characters the three species are quite similar, except for the absence of rays over two cells wide in D. guianensis. Instead of these, aggregate rays occur at intervals between consecutive rings of included phloem. D. mildbraediana possesses fibre tracheids with next to the normal large bordered pits numerous very large irregular slits giving the impression of a helical sculpturing of the walls. From a comparison with other Convolvulaceous genera like Bonamia, Ipomoea, Maripa, Neuropeltis, and Prevostea¹ it appears that nearest to Dicranostyles in general appearance as well as in anatomical structure is the genus Maripa. The resemblance to Ipomoea seems only superficial. The relation between anatomical conformities of genera and their position in the various systems of subdivision of the family is discussed.
17 citations
TL;DR: Drought had little effect on dietary quality for gemsbok, but pronghorn are more dependent upon precipitation, which may be important to consider in light of increasing drought frequency associated with climate change.
Abstract: Species with a long evolutionary history of sympatry often have mechanisms for resource partitioning that reduce competition. However, introduced non-native ungulates often compete with native ungulates and competitive effects can be exacerbated in arid regions due to low primary productivity. Our objectives were to characterize diet composition, quality, and overlap between American pronghorn Antilocapra americana and introduced non-native gemsbok Oryx gazella in southcentral New Mexico, USA. Severe drought occurred between 2010 and 2011, which allowed us to evaluate drought impacts on diet composition, quality, and overlap. Using feces collected from each species, we assessed diet composition and overlap with microhistological analysis and diet quality using fecal nitrogen (FN) and fecal 2,6-diaminopimelic acid (FDAPA). Pronghorn diet was primarily composed of shrubs in the cool—dry season (64.5%) then shifted to forbs in the warm—dry (64.7%) and warm—wet (54.1%) seasons. Pronghorn diet also shifted to ...
17 citations
Cites background from "Anatomy of the Dicotyledons."
...…veins, silica, cell size and shape, shape of cell wall, stomata size, stomata shape and orientation, and associated companion cells, shape and number of cells making up the base of the trichome, and the presence of crystals (Metcalfe and Chalk 1950, Metcalfe 1960, Sparks and Malechek 1968)....
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TL;DR: The leaf and silicule trichomes of 18 species of Alysseae were studied by scanning electron and light microscopy and the trichome of the morphologically related species Alyssum pirinicum and A. cuneifolium provide additional reliable features to distinguish them.
Abstract: Ancev, M. & Goranova, V.: Trichome morphology of eleven genera of the tribe Alysseae (Brassicaceae) occurring in Bulgaria. — Willdenowia 36 (Special Issue): 193–204. — ISSN 0511-9618; © 2006 BGBM Berlin-Dahlem. doi:10.3372/wi.36.36116 (available via http://dx.doi.org/) The leaf and silicule trichomes of 18 species of Alysseae were studied by scanning electron and light microscopy. Four trichome types are distinguished: (1) simple, (2) stalked 2- to 5-armed, (3) stellate and (4) dendritic trichomes. (1) Simple trichomes cover the leaves of Lunaria rediviva and, mixed with stalked 2- to 3-armed ones, compose the leaf indumentum of Camelina sativa. The simple trichomes on the silicules of Clypeola jonthlaspi subsp. microcarpa are columnar with transverse furrows. (2) Stalked 2-5-armed trichomes are present on the leaves of Draba korabensis, D. muralis, D. siliquosa and Erophila verna subsp. spathulata. Peculiar stalked trichomes with swollen globular base occur on the lower leaf surface of D. murali...
17 citations