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1.
Crystals and their taxonomic significance in some Verbenaceae   总被引:1,自引:0,他引:1  
MATHEW, L. & SHAH, G. L., 1984. Crystals and their taxonomic significance in some Verbenaceae. The morphology, plant distribution and chemical composition of crystals in 35 tropical species in the family Verbenaceae have been investigated using light microscopy, SEM and an energy dispersive X-ray analyser.
Crystals may be solitary, aggregated or as conglomerates and crystal sand. Eleven kinds of solitary crystals and five aggregate or conglomerate forms have been observed. Their occurrence varies from species to species and sometimes from organ to organ in the same plant, suggesting that there might be taxonomic significance of crystal form and distribution.
Most of the crystals are compounds of a range of elements, silicon, calcium, potassium, iron, magnesium, aluminium, sulphur sodium and titanium in varying proportions. Calcium is the major component of solitary acicular crystals and silicon of other kinds of crystals.  相似文献   

2.
Original and published data on the structure of egg teeth in squamate reptiles and the phylogenetic significance of corresponding characters are reviewed, elaborating A.M. Sergeev’s ideas on the subject. Problems are discussed concerning the use of this character in modern phylogenetic constructions and the necessity of new embryological investigations to resolve the issue concerning the formation of an unpaired egg tooth rudiment in all Squamata except the Dibamidae and Gekkota.  相似文献   

3.
Abstract

The deciduous premolars of early Eocene Equidae from North America, conventionally attributed to ‘Hyracotherium’, are described and compared, based primarily on a sample of >60 specimens from the early Eocene Willwood Formation of the Bighorn Basin, Wyoming. The sample represents six to nine species assigned to multiple genera by some other authors, but in the absence of diagnostic characters of the deciduous dentition, species assignments remain ambiguous for most specimens. Consequently it is not clear which generic names should be applied, and we employ the widespread name ‘Hyracotherium’ (acknowledging that the type species may not be an equid). We observed considerable variation in our sample, but most differences are minor and are largely inconsistent with respect to time or taxa, hindering attempts to characterise deciduous premolar anatomy of particular species. Comparisons were also made to Bridgerian Orohippus and Uintan Epihippus, to other early perissodactyls, and to non-perissodactyls that have been considered close to the origin of Perissodactyla (phenacodontid condylarths and Cambaytherium). Based on these comparisons, we confirm Butler’s observation that the deciduous premolars of equids show increasing molarization and lophodonty through the Eocene. However, our evidence suggests that there was little directed change through most of the Wasatchian until Wa-7.  相似文献   

4.
Documentation of amentoflavone O-glucosides as the predominant flavonoid glycosides in both genera of the Psilotaceae clearly distinguishes this family from all other families of vascular plants. Psilotum and Tmesipteris also possess apigenin C- and O-glycosides as common flavonoid types. Apigenin 7-O-rhamnoglucoside occurs in both genera and the previously undocumented apigenin 7-O-rhamnoglucoside-4′-O-glucoside, although identified only in Tmesipteris, may also be present in Psilotum. The existence of flavone C-glycosides in both genera may provide a phytochemical relationship between the Psilotaceae and some ferns. The phylogenetic significance of these results is discussed.  相似文献   

5.
P. M. Butler    E. Nevo    A. Beiles    S. Simson 《Journal of Zoology》1993,229(2):191-216
This study compares and contrasts variations of enamel fold pattern on the crowns of the molars of subterranean mole rats ( Spalax ) belonging to two superspecies, S. ehrenbergi and S. leucodon , and involving about 20 chromosomal species, distributed parapatrically and ranging on different soil types. The sample studied involved 397 skulls, subdivided as follows: 280 of S. ehrenbergi from Israel, representing the four chromosomal species 2n = 52, 54, 58 and 60; 59 of S. ehrenbergi from Egypt, Lebanon, Syria, Jordan and Turkey; 58 of S. leucodon from Turkey.
In making the comparisons it was necessary to take into account the marked changes of molar pattern that take place as a result of wear.
There is a reasonably good agreement between differences of molar pattern and genetic and immunological distances. The species in Israel and Egypt form a compact group, clearly differentiated from Turkish leucodon; ehrenbergi from Turkey and Syria are intermediate, in accordance with their geographical distribution.
In Israel, differences associated with soil type are at about the same level as differences between species. Local populations show a higher level of diversity, and in a number of cases neighbouring populations differed significantly, sometimes over very short distances. Population differences within species are generally associated with differences of soil and vegetation, indicating the influence of natural selection. There are also differences across species boundaries, implying a phylogenetic (heritage) effect. The nature of the adaptive link between molar pattern and soil is unknown: possible factors are contamination of the food by soil, and toughness of the food which necessitates changes of enamel fold length to improve grinding efficiency.  相似文献   

6.
甘草属(Glycyrrhiza)植物具“9 + 1”二体雄蕊, 其中9枚合生雄蕊的上部花丝分离, 分离的花丝在发育过程中存在由早期长、短交错的二组排列方式转变为后期以雄蕊管最长的1枚雄蕊为中心向两边渐次缩短的倒“V”形排列。为了解这种雄蕊发育动态、分化现象及发育成熟后的适应意义, 该文以光果甘草(G. glabra)为实验材料, 比较了雄蕊发育过程中的形态变化、成熟花粉的理化性质及在传粉中的作用。结果显示: 雄蕊发育早期长、短两组雄蕊在花药大小与形状上存在分化, 但后期伴随着花丝的快速生长与花粉的成熟、散出, 花药大小与形状趋于一致; 花粉组织化学成分及授粉成功率无差异, 但成熟花粉的数量和花粉活力存在差异; 去雄处理虽然使访花者在一天内的两个访花高峰期的访花频次降低, 但结实率高于自然对照, 说明以异交为主的花去除雄蕊后, 降低了雌、雄蕊间的功能干扰, 提高了传粉昆虫的授粉率; 发育早期长、短交错排列的二组雄蕊到成熟期时发生的倒“V”形排列的转变, 使不同数量与活性的花粉分布在花内不同空间, 最大化接触访花者, 实现了资源节约, 提高了雄蕊的雄性适合度, 即在有限的空间内用最节约的雄性资源投入、使传粉空间与传粉几率最大化的方式, 来提高雄性功能。  相似文献   

7.
The flavonoid chemistry of Takakia is described for the first time. T. lepidozioides, thought to be amongst the most primitive of extant liverworts, contains a high level and wide variety of flavone C- and O-glycosides, many of which are unique. New flavonoids include the 8-O-glucuronide and 8-O-xylosylglucoside of takakin (8-hydroxyacacetin), luteolin 6-C-arabinoside-8-C-pentoside, kaempferol 3-O-glucoside-7-O-xyloside and a number of tricetin C-glycosides. The only other known Takakia species, T. ceratophylla, contains the same 4 major constituents but significantly lacks flavonols. The often suggested relationship of Takakia with the order Calobryales is not supported by the available flavonoid data. Biochemical affinities of Takakia with all major liverwort orders are noted and the flavonoid data are interpreted as supporting the concept of Takakia as an isolated branch among the ancestors of modern bryophytes.  相似文献   

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Haowen Tong 《Geobios》2005,38(1):139
Most of the Quaternary tapir fossils from China are isolated teeth. The purpose of this paper is to identify them and to extract systematic and evolutionary information from them. Based on morphology and W/L ratio, isolated teeth can be identified successfully. On the whole, the identification of P1, M3 and P2 is believed to be reliable, while it is difficult to distinguish P3 from P4, M1 from M2 etc. Concerning the variations of the teeth, P1 is the most variable one in dimension. In the Quaternary tapirs in China, some dental characters can be used as reliable indicators to evaluate their evolutionary levels. The degree of the atrophy of the upper canine relative to the caniniform I3 is reflected in the C/I3 diameter ratio, which is decreasing during evolution. P1 changes considerably in outline and strength of the hypocone. Some forms are without hypocone, such as Tapirus sanyuanensis, some have a very faint hypocone, such as Tapirus indicus; although most of them show a developed hypocone. For other cheek teeth, the W/L ratio is decreasing through geologic time. Two lineages can be tentatively proposed: one is the Tapirus peii-Tapirus sinensis-Megatapirus augustus progression; the other is the T. sanyuanensis-T. indicus lineage. T. sanyuanensis and T. peii stand on the base, and it is very probable that the latter is more primitive.  相似文献   

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Ultrastructure and differentiation of penis stylets and stylet needles have been investigated in representatives of various groups of free-living platyhelminths, viz. the Acoela, Macrostomida, Typhloplanoida, Kalyptorhynchia, and Dalyellioida. In all these groups, the differentiation of such hard parts occurs intracellularly but in different ways in the different groups. The ultrastructure of the bursal mouth piece in an acoel platyhelminth is not comparable to the hard structures in male copulatory organs. The presence of penial copulatory organs having intracellular hard structures appears to be an autapomorphy of the Euplatyhelminthes. Several characters in the ultrastructure and development of these structures can be used as autapomorphies for various platyhelminth groups.  相似文献   

12.
Lateralisation, the different use of one or other side or appendix of the body, is basically determined by brain asymmetry which, in turn, is likely to be due to adaptive reasons. Several studies have been carried out on birds in general. However, birds of prey in particular, although they are very good candidates, have not been investigated from the sensory lateralisation point of view. In fact, many species scan for prey while perched and capture terrestrial prey with the feet, having at the same time the obvious necessity to keep their balance. This paper, therefore, investigates the existence of some sort of lateralisation in several species of both Falconiformes and Strigiformes temporarily in captivity. Attention is given to: (a) the direction of body rotation when perceiving a sound stimulus from behind the body and (b) the use of the feet when grasping a terrestrial prey. Lateralisation was found to be clearly present in both types of tests, although with some difference in its expression. In fact, almost every species tested rotated its body anti-clockwise, i.e. to the left, both in the first test and in repeated tests, with no noticeable difference between Falconiformes and Strigiformes. Also prey grasping showed a preferential use of one foot. Falconiformes preferred clearly to grasp the prey with one foot only in both the first test and in subsequent ones. Strigiformes, on the other hand, preferred using both feet, although a not insignificant proportion of individuals used one foot. Only the little owl seemed to have the tendency to prefer to use the right foot only, in a similar manner to Falconiformes. In fact, this bird is the most "diurnal" owl species among those tested, suggesting that lateralisation in footedness might be affected by adaptive constraints more than by phylogenetic similarities. Lateralisation, therefore, seems to be very widespread among birds of prey. Preferential use of the right foot also appears to be a general habit, and this is probably connected to the use of left hemisphere when manipulating food items.  相似文献   

13.
The column is the most characteristic part of an orchid flower. It is considered to be formed by the union of stamens with a central style and stigma. In the Apostasieae, for example, the column is rather primitive in the stamens and style only partially united, whereas in the majority of higher orchids it becomes more advanced through a eomplete union of them into a single organ. Within the family, indeed, the column structure is greatly diversified and of great taxonomic significance. It is interesting to note that a great range of diversity of column structure is bund in Neottia (sensu lato), a small but widespread genus consisting of 14 species, about two thirds of which, however, are of local occurance and seem to be little known to many botanists. In some speeies of this genus we find a very primitive column structure which is quite unique in the family, while in the others it is much more complicated. In all, five types of their column structure can be distinguished as fol- lows: (1) column rather longer; anther erect with a short filament attached to the back of the column near the apex; stigma terminal; neither clinandrium nor rostellure; (f. 2, 4) (2) as the preceding, 'except for the stigma more or less curved foreward and filament longer; (f. 6, 8) (3) column rather longer with a clinandrium at its summit, upon which a sessile and incumbent anther sits; rostellum large, horizontally projecting out over the concave stigma situated in the front of the column; (f. 10, 13, 15, 17) (4) as the preceding, except, for the anther and rostellum almost erect, and the stigma more or less bilabiate; (f. 19,21) (5) column very short; anther and rostellum erect; stigma lamellate, erect; reflexed and almost clasping the rostellum. (f.,2g) In these .five types, with the exception of the first one in which the labellum (the median petal) is very similar to the lateral: petals, they all possess zygomorphic perianth with labellum bilobed or entire which is quite different from the two lateral petals. Here, we see a great change in the column structure from one form with stamen and style not fully united to another form in which they have been well fused. Speaking strictly, these are two sorts of entirely different column structure. The former one, represented by (1) and (2) as stated above, is, in fact, an incomplete or s very primitive column in having a terminal stigma and an erect stamen with its free filament attached to the back of the column; and the absence of clinandrium and rostellum. Furthermore, there exists on the back of the column a thick ridge with its upper end joined to the filament, with which it is of the same texture and appearance. In Neottia pantlingii (=Arohineottia pantlingii) the free filament is even rather longer than the ridge, (f. 6) while in the other three species (f. 2, 4, 8) they are shorter. It is in my opinion the lower part of the filament adnate to the compound style or column. This is another fact of interest perhaps not occuring in any other living orchids. On the other hand, the latter one, represented by (3), (4) and (5), is a more advanced column structure, in which a higher level of specialisation with well-developed clinandrium and rostellum is reached. The stigma becomes shallow depressed on the anterior side of the column, or sometimes in the form of somewhat a bilabiate lip projecting out before or under the long rostellum. This is apparently a complete column both in structure and function quite different from the former and, contrarily, much like that of Listera. Basing upon the facts just mentioned, we may subdivided Neottia (sensu lato) into two distinct genera, with two and three sections respectively. They are as follows: 1. Archineottia S. C. Chen, gen. nov. (1) Sect. Archineottia 1) A. gaudissartii (Hand.-Mzt.) S. C. Chen, comb. nov. (China) 2) A. microglottis (Duthie) S. C. Chen, comb. nov. (India) (2) Sect. Furciila S. C. Chen, sect. nov. 3) A. pantlingii (W. W. Smith) S. C. Chen, comb. nov. (Sikkim) 4) A. smithiana (Schltr.) S. C. Chen, comb. nov. (China) 2. Neottia Guett. (1) Sect. Listeroides S.C. Chen, sect. nov. 1) N. listeroides (L.) Rchb. f. (China, Sikkim, Kashmir) 2) N. camtschatea (L.) Rchb. f, (China, Soviet Union) 3) N. megalochila S. C. Chen, nom. nov. (China) 4) N. inayatii (I)uthie) Schltr. (Pakistan, Kashmir) 5) N. tenii Schltr; (China) (2) Sect. Neottia 6) N. papilligera Schltr. (Chinas: Japan, Korea, Soviet Union, Sikkim) 7) N. nidus-avis (L.) L. C. Rich. (Europe, Iran, Western Siberia) 8) N. brevilabris Tang et Wang: (China) (3) Sect. Hologlossa S. C. Chen, sect. nov. 9) N. acuminata Schltr. (China, Japan, Korea, Soviet Union, Sikkim) Inperfeetly known species: 10) N. ussuriensis (Kom. et Nevski) S6o (Soviet Union) Thus, the subtribe Neottiinae are composed of four genera, namely, Diplandrorchis, Archineottia, Neottia and Listera. The new genus Archineottia, as one of the most primitive genera in the family, is of great interest from a phylogenetic point of view. It shows dose similarity to Diplandrorchis and Neottia in habit, but sharply distinct from them in column structure. These genera, as indicated By some authors, also show affinity in some respects with the subtribe Limodorinae, especially to Tangtsinia and Sinorchis, the other two quite primitive genera in the family. There is, indeed, a great need of further study of these interesting or relic genera and this, I think, would go a long way towards solving the problems concerning the origin ofthe Orchidaceae.  相似文献   

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不同温度对七种外来杂草生理指标的影响及其适应意义   总被引:14,自引:1,他引:14  
郭水良  方芳  强胜 《广西植物》2003,23(1):73-76,82
加拿大一枝黄花(Solidagocanadensis)、小飞蓬(Conyzacanadensis)、野塘蒿(Conyzabonarinsis)、钻形紫菀(Astersublatus)、一年蓬(Erigeronannuus)、马缨丹(Lantanacamara)和金鸡菊(Coreopsislanceolata)是我国东南地区有分布的7种外来杂草。测定了38°C、25°C和5°C处理下它们的可溶性糖、脯氨酸、丙二醛含量和过氧化物酶活性。结果表明,7种杂草对高温的耐受能力,由大到小分别为野塘蒿、小飞蓬、钻形紫菀、加拿大一枝黄花、马缨丹、一年蓬和金鸡菊,对低温的耐受能力,由大到小则分别为野塘蒿、小飞蓬、马缨丹、一年蓬、钻形紫菀、加拿大一枝黄花和金鸡菊。分析了四种生理指标变化的生态适应意义。  相似文献   

20.
The external morphology of the compound eyes of 13 species of the Ascalaphidae family (Insecta, Neuroptera) from Africa, Asia and Europe was studied in relation to the habitat, phylogeny and time of activity during the day. The six species with undivided eyes (Haplogleniinae) are nocturnal; four inhabit more or less open terrain, while two inhabit more or less dense vegetation. Of the seven species with divided eyes (Ascalaphinae), three are diurnal, one is crepuscular and nocturnal, and three are nocturnal. It was found that two of the diurnal species inhabit open terrain and open forest, and one inhabits dense vegetation; the crepuscular and nocturnal species inhabits open terrain; and two of the nocturnal species inhabit open terrain, while one inhabits dense vegetation. The results are discussed in relation to the hypothesis that divided eyes evolved from undivided eyes, originally serving as an adaptation to daytime vision in open terrain.  相似文献   

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