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41.
42.
Charcoal remains were analysed from copper ore smelting at Khirbet en-Nahas, an Iron Age site in the region of Feinan between Wadi Arabah and the highland of Edom. For the first time, a section was dug into a stratified slag heap and separate charcoal samples were taken from each layer. Radiocarbon dates from the charcoal range from the 12th to the 9th century B.C. The main aim of this work was to find out whether the fuel species spectra change or remain constant over the period of metallurgical activity covered by this slag heap. Twelve samples totalling 2257 pieces amounting to 340.58 g of charcoal were analysed. The species composition is more or less the same in all samples. 14 species were identified. Approximately 50% of the material consisted of Tamarix species, 40% was Retama raetam, Phoenix dactylifera and Haloxylon persicum. Thus, the rapidly regenerating shrub vegetation within walking distance of the smelting place was used as fuel and remained unchanged during at least two to three centuries. Trees from the highland of Edom such as Juniperus phoenicea or Quercus calliprinos were not found here, although they were identified from Early Bronze Age sites a few kilometres up the wadis.  相似文献   
43.
The possible alliance between Gaertnera and Pagamea (Rubiaceae-Rubioideae), two genera from the Old and New World, respectively, is investigated on the basis of wood anatomy and pollen morphology. Nowadays, the main point of discussion about the taxonomic position of these genera is whether they belong to the Psychotrieae or constitute a tribe Gaertnereae characterised by their secondarily superior ovary and sheathing stipules. Both the wood and pollen of the genus pair are found to show specific features absent in other genera of the Psychotrieae, e.g. parenchyma bands in the xylem and endexine thickenings on the polar sites of the pollen apertures. Nevertheless Gaertnera and Pagamea share many other characters with the Psychotrieae. Wood and pollen convincingly demonstrate the very close affinity of the two genera. The sister pair differs in so many features from other Psychotrieae, that Gaertnera and Pagamea should constitute at least a subtribe Gaertnerinae, formally recognized here. The general lack of profound studies on the affinities within the very large tribe Psychotrieae makes further comments on the taxonomic relationships of the Gaertnerinae difficult.  相似文献   
44.
通过发育解剖学研究表明,秦艽根的初生结构正常,初生木质部四原型。次生生长早期阶段也是正常的,但天以后的次生生长过程中,由于木质部内部分薄壁细胞的分裂,且迅速 化成异常形成层细胞,并与原维管形成层相连,从而形成多个新的形成层环,将木质部柱分为几个子木质部。  相似文献   
45.
贺兰山不同生境旱生灌木的解剖学研究   总被引:9,自引:1,他引:8  
贺兰山荒漠地带三种不同基质生境的20种旱生灌木的营养器官的比较解剖学研究表明:其共同特点是叶片的表面积/体积的比值小,叶表具厚的角质层、表皮毛,气孔下陷、并具孔下室,叶向中栅栏组织发达;轴器官中木栓层细胞层数多,皮层较厚,机械组织发达,木薄壁组织及髓部细胞的细胞壁术化加厚,根内都具周皮、木质部的导管分子大小不一、频率较高。此外,根、茎、叶中普遍存在粘液细胞和草酸钙结晶,部分植物的根和茎内有异常维管组织。这些结构特征都与早生环境相关,而不同基质生境中生长的植物尚存在一定差异。  相似文献   
46.
银缕梅木材解剖特征及其系统学意义   总被引:5,自引:0,他引:5  
报道了银缕梅(ShaniodendronsubaequaleM.B.Deng,H.T.Wei&X,Q,Wang)木材的解剖学特征,通过比较研究支持将银缕梅(“小叶金缕梅”HamamelissubaeqalisH.T.Chang)从金缕梅属(族)中分出的处理,其合适的系统位置应归入弗特吉族。  相似文献   
47.
48.
Polyethylene glycol was used to induce water stress of micropropagated Valiant grape. Reduced growth and slow rooting were observed in treated plantlets with 2, 4 and 6% polyethylene glycol as compared to control plantlets with no polyethylene glycol in the rooting medium. At high concentrations of 4 and 6%, leaves exhibited wilting and necrosis. At the 2% level, plantlets recovered and grew satisfactorily. Detached leaves of treated plantlets with 2% polyethylene glycol lost less water than controls when exposed to low humidity for 4 hours. Leaf anatomy of plantlets treated with 2% polyethylene glycol, control (in vitro plantlets) and greenhouse-grown plants were compared under light microscopy. Leaves from control plantlets contained larger mesophyll cells, lacked normal palisade layer formation, had greater intercellular pore spaces and fewer chloroplasts. Leaves from polyethylene glycol-treated plantlets, however, had smaller mesophyll cells, a more defined palisade layer, reduced intercellular pore space and the greatest number of chloroplasts. These results suggest that an osmoticum such as polyethylene glycol may be used to induce more normal leaf anatomy and reduced water loss in micropropagated Valiant grapes.Abbreviations BA 6-benzylaminopurine - FAA formalin-acetol-alcohol - MS Murashige & Skoog (1962) medium - MW molecular weight - NAA napthaleneacetic acid - PEG polyethylene glycol - TBA tertiary butyl alcohol  相似文献   
49.
The capitular and floral morphology and anatomy ofBidens L. andCoreopsis L. were studied. All the North American species ofCoreopsis were studied. Selected species ofBidens from North and South America andCoreopsis from South America were included. The results were compared with previous observations on African species ofBidens (incl.Coreopsis). Emphasis was given to character states of the ray florets, paleae, stylearm apices, outer phyllaries, achenes, and pollen grains. Some of the character states are unique features ofCoreopsis, e.g., globular and elongately conical receptacles, deltoid outer phyllaries, truncate and indistinctly 3–5-dentate, 3–4-lobed ray florets, narrowly spathulate paleae, subulate paleae with linear-filiform upper half, hairy and apically 3-cleft paleae, truncate, convex or shallowly conical stylearm apices with the sweeping hairs limited to the area above the stigmatic surfaces and the orbicular to circular achenes. The cylindric setaceous pappus bristles so commonly encountered inBidens are unknown inCoreopsis. The pappus bristles inCoreopsis are paleaceous but similar, though thicker ones are also found in African species ofBidens (incl.Coreopsis) with winged achenes. Twin-celled hairs (setulae) with differing degrees of wall thickness are found on the achenes ofCoreopsis sect.Pseudoagarista (Mexico and South America),Coreopsis sect.Pugiopappus (California), AfricanBidens with winged achenes (e.g.,B. prestinaria, B. macroptera) and some North AmericanBidens (e.g.,B. aristosa). Similar sclerotic parenchyma make up the achenial wings of species in both genera. These may be interpreted as homologous structures, indicating the underlying similarity of these taxa and their derivation from a common ancestral stock.  相似文献   
50.
 For the angiosperm dominants of northern California’s mixed evergreen forests, this study compares the display of photosynthetic tissue within leaves and along branches, and examines the correspondence between these morphological attributes and the known environmental tolerances of these species. Measurements were made on both sun and shade saplings of six species: Arbutus m e n z i e s i i (Ericaceae), C h r y s o l e p i s c h r y s o p h y l l a (Fagaceae), L i t h o c a r p u s d e n s i f l o r u s (Fagaceae), Quercus c h r y s o l e p i s (Fagaceae), Quercus w i s l i z e n i i (Fagaceae), and Umbellularia c a l i f o r n i c a (Lauraceae). All species had sclerophyllous leaves with thick epidermal walls, but species differed in leaf specific weight, thickness of mesophyll tissues and in the presence of a hypodermis, crystals, secretory idioblasts, epicuticular deposits, and trichomes. The leaves of Arbutus were 2 – 5 times larger than those of C h r y s o l e p i s, L i t h o c a r p u s and Umbellularia and 4 – 10 times larger than those of both Quercus species. Together with differences in branch architecture, these leaf traits divide the species into groups corresponding to environmental tolerances. Shade-tolerant C h r y s o l e p i s, L i t h o c a r p u s, and Umbellularia had longer leaf lifespans and less palisade tissue, leaf area, and crown mass per volume than the intermediate to intolerant Arbutus and Quercus. Having smaller leaves, Quercus branches had more branch mass per leaf area and per palisade volume than other species, whereas Arbutus had less than other species. These differences in display of photosynthetic tissue should contribute to greater growth for Quercus relative to the other species under high light and limited water, for Arbutus under high light and water availability, and for C h r y s o l e p i s, L i t h o c a r p u s, and Umbellularia under limiting light levels. Accepted: 22 March 1996  相似文献   
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