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1.
Limnocharis flava ( Linn. ) Buch. normally produced 2 ~ 13 bisexual flowers in a cincinnus (seorpioid cyme). The anthesis of each flower lasted 5 ~ 13 hours. In natural populations, two species of beetles were observed visiting the flowers in bloom. Several whorls of staminodes outside of the stamens limited the pollen to disperse outward, and made the pollen deposit only on the stigma of the same flower. After the perianth closed, the inner perianth changed into liquid which created a suitable environment for pollen germination. The pollen-ovule ratio, which ranged from 650 to 1120( 930±180) reflects an economical self-pollination system. As the fruits maturied, the inflorescence fell to ground or mud, and the vegetative buds (i.e. vegetative components ), developed at the apex of the inflorescence, grew into new vegetative shoots. One mother plant usually could produce 6 ~ 20 new vegetative shoots in a life cycle. One fruit of L. flava contained 470 ~ 640 seeds, with an average seed-set rate of about 80%. The seeds of Limnocharis flava could disperse a long distance and occupy new suitable habitats to establish new populations. The vegetative buds, however, predominantly could only spread to nearby places and thus enlarge the size of the population. Results from some artificial treatments, such as emasculating and netting, emasculating and bagging, hand-pollinating, netting, and bagging, indicate that L. flava is selfing in general but also cross-compatible. Based on the above results, it is considered that the breeding system of L. flava is predominantly selfing, but mixed with outcrossing, and the likely evolutionary tendencyis from outcrossing to selfing.  相似文献   

2.
Two leafy specimens of Tingia carbonica were collected as impression from Shanxi formation of Permian, from Inner Mongolia, China. The epidermal structure of its leaves is reported in this paper. Under SEM, well preserved epidermal cells as well as some concaves on the surface of large leaves were clearly recognized. The epidermal cells are approximately rectangular in shape, about 100~150 um long and 20~30 um wide. They are arranged longitudinally parallel to veins. The concaves usually in rows are round or elliptical, about 0.65~0.35 mm long and 0.2~0.35 mm wide. Density of concaves is about 1.8/ mm2 and no stomata occur inside the concaves. In all probability, this is the upper epidermis. On the other side of the epidermis, anomocytic stomata are scattered irregularly, each with 5~6 epidermal cells around. The stomatal apertures are about 35.8 µm long, and 18.7 um wide, which is organised parallel to the common epidermal cells. As far as shape and size is concerned, it is similar to that described on the upper epidermis. Density of the stomata is about 60/mm2. In all Probability, this is the lower epidermis. The ecological preference and classification of Tingia are discussed according to these new characters of the epidermis andsubordinate struture of the leaf.  相似文献   

3.
Rhododendron longesquamatum var. glabristylum Y. Y. Geng et Z. L. Zhao , a new variety of the Ericaceae from Sichuan, China, is described and illustrat ed. This variety is different from the typical one by having smaller leaves (5~8×2~3.5 cm) and smalle  相似文献   

4.
王文采 《广西植物》2016,36(Z1):209-210
描述了自广西发现的荨麻科赤车属一新种,来宾赤车。此种与特产云南东南部的富宁赤车相近缘,与后者的区别在于本种茎的毛开展或向上弯曲,叶片长椭圆形,基部斜楔形,雌花具3~4枚花被片,其中1~2枚较大花被片在背面顶端具一长筒状突起。  相似文献   

5.
Two new species of platanoid reproductive structure are described from the Bull Mountain locality in the Patapsco Formation (Potomac Group) of northeastern Maryland, USA. Pistillate inflorescences and infructescences (Platanocarpus elkneckensis sp. nov.) consist of flowers and fruits in sessile globose heads that are borne on an elongate axis. Individual pistillate flowers consist of five free carpels surrounded by prominent tepals. Staminate inflorescences, flowers and isolated stamens are assigned to Hamatia elkneckensis gen. et sp. nov. Staminate flowers are borne in a globose head with a small number of stamens (five?) per flower. Stamens consist of very short filaments, long anthers with strongly valvate dehiscence and an apically expanded connective. The connective expansion is frequently very well-developed, hook-like and extends down the ventral surface of the stamen. Anthers contain small, tricolporate, reticulate pollen. Association evidence, similarity of inflorescence structure and the occurrence of Hamatia-type pollen on flowers, carpels and fruits of Platanocarpus elkneckensis suggests that the staminate and pistillate material was produced by a single species of plant. The “Hamatia-plant” provides further evidence of pentamerous floral structure in mid-Cretaceous platanoids and documents the occurrence of unequivocal tricolporate pollen in the platanoid complex.  相似文献   

6.
7.
Oxalis jiayinensis, sp. nov., is described from the Late Cretaceous (TuronianSenonian) in Jiayin County, Heilongjiang Province, northeastern China. The seed is about 1 mm long, less than 1 mm in diameter, crescentic with obtuse apices and 9~10 transverse ribs. The seed wall is composed of equiaxial, strongly thickened sclereids. The fossil repre-sents the oldest occurrence of the family Oxalidaceae in the world.  相似文献   

8.
Compressions and impressions of leafy twigs, pollen cones, and seed cones of Athrotaxites berryi are abundant in certain layers of the Kootenai Formation (Aptian) in Montana and the Lower Blairmore Formation in adjacent Alberta. The twigs are densely covered by helically arranged leaves that are about 2 mm long and wide. Pollen cones are borne laterally on ultimate branch segments. Some are sessile, while others terminate a minute lateral branch. The cones are 3–4 mm in diam and about 10 mm long. Each sporophyll has a stalk that is about 0.7 mm long and an upturned laminar tip that is 1–1.5 mm long by 1 mm wide. At least two pollen sacs are attached to the abaxial side of each sporophyll. Seed cones are borne terminally on lateral branches that are often curved. These cones are about 10 mm at their widest diameter and about 15 mm long. Each bract and associated ovuliferous scale are fused to form a wedge-shaped complex that is 4–5 mm long. The complex is 0.7 mm wide at its base and expands to about 2.5 mm wide and thick near its apex. The tip of the complex narrows abruptly to a point and terminates in a spine that is about 0.5 mm long. At least one seed occurs on the adaxial side of each complex. Athrotaxites berryi belongs to the Taxodiaceae. It resembles modern Athrotaxis cupressoides but differs from it in too many aspects to be included in the modern genus.  相似文献   

9.
A new genus of Phytolaccaceae,Nowickea, includes two new species,N. xolocotzii andN. glabra, each known only from its type locality in the states of Jalisco and Morelos, Mexico, respectively.Nowickea exhibits close relationship withPhytolacca by a robust herbaceous growth habit, 7- to 10-carpellate ovary, carpels with terminal, basally connate styles, basal placentation, and fleshy fruits. It is distinguished by green, subequal, herbaceous, and often lanceolate tepals 3 to 12 mm long, ovary and fruit elevated on a well developed gynophore, obovoid or obpyriform fruits, and narrowly ellipsoid seeds.  相似文献   

10.
An Early Devonian flora from the Pingyiqu Formation of northern Sichuan is described. It contains 13 species in 9 genera. They are Eogaspesiea gracilis, Uskiella sp., Zosterophyllum myretonianum, Z.yunnanicum, Z.sichuanense sp.nov., Oricilla unilateralis sp.nov., Hicklingia cf.edwardii, Psilophyton sp., Drepanophycus spinaetormis, D.spinosus, D.sp., Leclercqia complexa, and Sciadocillus cuneifidus gen.et sp.nov. The geologic range of the flora is inferred to be Siegenian (probably Upper Gedinnian-Siegenian). Sciadocillus gen.nov. (Marchantiales?) Diagnosis: Thalli flattened, composed of a central disc-like structure and radiating wedge-shaped unbranched lobes. Sporangium-like reproductive organs round to elliptic, attached to the upper surface and along the edges of the lobes. Spores trilete. Type species: Sciadocillus cuneifidus Sciadocillus cuneifidus sp.nov. Thallus, 4.2mm in diameter, consists of a central disc-like structure, about 1.0mm in diameter, bearing 14 unbranched lobes. Lobes wedge-shaped, 1.5-1.75mm long , 0.75-0.83mm wide at the apex and 0.25mm at the base. Sporangium-like reproductive organs round to elliptic, 0.45-0.50mm long and about 0.4mm wide, without stalks. Spores, spheroidal to subspheroidal, 20-40μm in diameter, trilete, exine smooth, sometimes folded. Holotype: Plate 7:53, 54 (counterpart). Locality: Approximately 800m, in northwest Yanmenba Village, Jiangyou, Sichuan. Horizon: Lower part of Pingyipu Formation (Upper Gedinnian-Siegenian). Zosterophyllum Penhallow (1892) (Zosterophyllaceae) Zosterophyllum sichuanense sp.nov. Plant with smooth axes at least 57mm long, 1.6-2.0mm wide, branching unknown. Fertile axes terminate in lax spikes, about 6.5mm wide; spikes with spirally arranged sporangia, three to four gyres. Sporangia borne on stalks, 2.7-3.9mm long and 0.54-0.81mm wide; stalks obliquely inserted on axis, gentely cured upwards, in profile often C-shaped with adaxial margins of sporangia; stalk contain vascular strand. Sporangia Fan-shaped, often folded in half and margins facing axis, almost triangular in side view, sometimes obovate in abaxial view; dehiscense not observed. Holotype: Plate 2:11. Paratype: Plate 2:10, 14. Locality: approximately 800m, northwest Yanmenba Village, Jiangyou, Sichuan. Horizon: Pingyipu Formation (Siegenian). Oricilla Gensel (1982) (Zosterophyllaceae) Oricilla unilateralis sp.nov. Plants erect. Naked axes at least 76mm long, 1.6-3.2mm wide, branching dichotomous with branching angles 30-60°in fertile regions. Sporangia borne laterally in one row on branches, located above bifurcation, oriented to inside of axis. Stalks not observed. Sporangia probably attached by an extremely short stalk to axis at right angle. Sporangia reniform to ellitical, 2.8-4.0mm wide (X=3.3mm), 2.0-2.5mm high (X =2.3mm) , composed of two equal valves, dehiscent along distal margin. Spores subcircular, trilete, 48-58μm, in diameter, smooth, with dark area at juncture of trilete rays. Surface covered with tapetal residue. Holotype: Plate 4: 28. Paratype: Plate 4: 30-32. Locality: Approximately 800 m northwest Yanmenba Village, Jiangyou, Sichuan. Horizon: Pingyipu Formation (Siegenian).  相似文献   

11.
Disporum jinfoshanense X. Z. Li, D. M. Zhang & D. Y. Hong, a new species of the Liliaceae from Nanchuan, Chongqing, China, is described and illustrated. This species is morphologically similar to D. smilacinum A. Gray in having leaves ovate to elliptic, inflorescences terminal, flowers spreading, tepals white, slightly saccate at the base, but differs from the latter in having stems dwarf, 15–20 cm tall, leaves 3–4, all on the upper part of the stems, petioles 2–4 mm long, and tepals densely pubescent on the inner surface.  相似文献   

12.
Two different types of dispersal units (called fruits in this study) were observed inSalsola komarovii Iljin. One is a fruit which has dark brown lignified tepals with long wings and a green seed and falls easily from the mother plant (long-winged type). Another has light brown lignified tepals with short wings and a yellow seed and attaches tightly to the mother plant (short-winged type). This difference of fruit type appeared independently from maturity of fruit. Seeds in the short-winged fruits were in dormancy for a longer period of time than those in the long-winged fruits. The germination rate was significantly higher in the seeds of long-winged fruits. The dormancy in seeds of the long-winged fruits was effectively terminated by reducing the temperature but the effect of chilling was very weak in seeds of the short-winged fruits. It was concluded from these observations that there exists a dimorphism in the fruits of, or a heterocarpy in,S. komarovii. The plants grown under water stress produced mostly short-winged fruits and those grown under well-watered conditions bore fruits of both types. Exogenously applied abscisic acid (ABA) tended to produce the short-winged fruits, suggesting that the heterocarpy was, at least partly, regulated by ABA.  相似文献   

13.
The pollen grains of 32 species, 1 subspecies and 4 varieties of Vitis and 1 species of Muscadinia were scanned with Hitachi S-800 scanning electron microscope and described in the present paper. In Vitis, the pollen morphology is found to be valuable for the identification of species, though it is of little significance in supraspecific classification and systematic consideration. The ornamentation of Vitis could be divided into four types: ( 1 ) The pollen grains are oblate or rarely spheroidal (P/E =0.97 ~ 1.08) in shape, with colpi wide enough to show dense granulae inside. The pollen grains of V. coignetiae Pull. Ex Planch. belong to this type. (2) The pollen grains are prolate to subprolate (P/E = 1.25 ~ 1.76 ), with sparse granulae within the colpi. This type includes l0 species, 1 subspecies and 3 varieties, such as V. hui Cheng etc. (3) The pollen grains of V. romanetii Roman du Caill. ex Planch. and V. davidii (Roman du Caill. ) Foex. var. ferruginea Merr. et Chun are prolate (P/E= 1.87 ~ 2.1), with colpi narrow and linear-shaped, but rhombic in the equational region. (4) The pollen grains are prolate or perprolate (P/E= 1.30 ~ 2. 0), with narrow and linear-shaped colpi. The species with this type of pollen grains are Muscadiniarotundifolia (Michx.) Small and 20 species of Vitis.  相似文献   

14.
王文采 《广西植物》2017,37(5):541-546
该文描述了荨麻科三新种:(1)自中国重庆市发现的荨麻科荨麻属一新种,城口荨麻。此种与异株荨麻有亲缘关系,区别特征为此种的茎被少数刺毛,叶片多为心形,雄、雌花序均不分枝,瘦果在中央稍凹陷。(2)自中国广西发现的荨麻科赤车属一新种,来宾赤车。此种与特产云南东南部的富宁赤车相近缘,与后者的区别在于本种茎的毛开展或向上弯曲,叶片长椭圆形,基部斜楔形,雌花具3~4枚花被片,其中1~2枚较大花被片在背面顶端具一长筒状突起。(3)自缅甸北部发现的荨麻科楼梯草属一新种,克钦楼梯草。此种在体态上与骤尖楼梯草甚为相似,与后者的区别在于本种的每一茎节具正常叶和一退化叶,托叶狭披针状条形和无脉,雌总苞苞片无角状突起,雌小苞片较大,呈楔状长圆形,雌花具一小花被片,以及雌蕊具一宽倒卵球形柱头。  相似文献   

15.
The rice genus (Oryza L. ) belongs to the grass family(Poaceae) and contains 24 annual or perennial species, including two cultivated rice species, i.e., the Asian rice ( O. sativa L. ) and African rice (O. glaberrima Steud. ), and 22 wild species distributed throughout the tropics of the world. Species in this genus have been extensively studied by scientists with different approaches, including morphological characterization and cytological and molecular investigations. The leaf epidermis is an important morphological character which has been studied for taxonomic identification and studies on systematic relationships of species, particularly in grasses. In this study, morphological features of the leaf epidermis of 23 rice species were observed through light microscopy. The results showed that some characters of the rice leaf epidermis had significant diversity between species and these characters were valuable for the identifying Oryza species, and for assessing systematic relationships in the genus. For example, O.schlechteri, O.ridleyi, O.longiglumis, O.granulata, and O. rneyeriana had elliptic stomatal complexes, whereas the other species had rhombic stomatal complexes. In most cases, papillae on the surface of the epidermis were variable in size and distribution between species. The size of papillae varied from small ( 1.5~4.4µm in diameter), medium-sized (9~18µm), to large (21~30µm) , and the pattern of papillary size and distribution were very useful for identification of rice species. In addition, the number and location of the small papillae in stomatal complexes were particularly different between species. Based on the following combinations of leaf-epidermic characters, i.e., the size and distribution of papillae on the abaxial surface of the epidermis, the number and location of the small papillae in stomatal complexes, and the shape of stomatal complexes, the 23 studied Oryza species could be divided into three major groups. The first group comprises O.longiglumis, O.ridleyi, O.meyeriana, and O.granulata. In these species, neither large nor medium-sized papillae, in some cases extremely rare small papillae, were found on the surfaces of epidermis, and there were no small papillae found in stomatal complexes. All species in the first group had elliptic stomatal complexes. The second group consists of O.brachyantha, diploid and tetraploid O.officinalis, O.minuta, O.eichingeri, O. punctata, O.latifolia, O.alta, O.grandiglumis, O.rhizomatis, and O.australiensis. In these species usually no large papillae were observed, but medium-sized and densely populated small papillae were found to cover the surface of epidermis, and at least four small papillae were found in stomatal complexes (in guard cells) of most species. The third group contains O.sativa, O.nivara, O.rufipogon, O.longistaminata, O. glumaepatula, O.meridionalis, O.barthii, O.glaberrima and O. schlechteri. The abaxial leaf epidermis of these species was usually covered with large papillae, medium-sized, and small papillae. In addition, more than 4 (usually 6~8 ) small papillae were found in guard cells or/and subsidiary cells of the stomatal complexes. Most species in the second and third groups had rhombic stomatal complexes. These results agree mostly with previous re-ports on the biosystematic studies of rice species by applying other methodologies.  相似文献   

16.
西双版纳热带季节雨林145个树种繁殖体特征   总被引:1,自引:0,他引:1  
分析了西双版纳热带季节雨林20公顷动态监测样地中145个树种的繁殖体特征。结果表明:雨季散布的种类最多(71.03%),在雾凉季及干热季散布的种类相对较少;果实类型以核果,蒴果,浆果居多,黑色、黄色、褐色果实最为常见;动物散布的种类最多(56.55%),其次为机械散布,独立散布,风力散布;大种子树种(种子最大长度〉10mm)较占优势(53.10%);树种单粒种子重量从2.3×10^-5~22.29g不等,但76.55%的种子的重量集中在0.01~10g之间;干热季散布的种子平均重量显著高于雨季和雾凉季;独立散布的种子重量最大,风力散布的种子重量最小,而机械弹射的种子重量和动物散布的种子重量之间差异不显著;树种的成年个体最大胸径与种子重量之间存在显著正相关。  相似文献   

17.
In the G2 line of peas (Pisum sativum L.), senescence of the shoot apex (which precedes leaf senescence) only occurs in long days (LD) though flowering is independent of photoperiod. It has been suggested that the photoperiodic control of senescence in G2 is mediated through different rates of seed growth. In LD seed growth is more rapid than in short days (SD) and this places a greater nutrient drain on the plant. In addition, more flowers develop into fruits in LD than in SD: 32% of flower buds abort in SD while almost none abort in LD. Senescence is associated with early seed growth and does not occur in deflowered or deseeded plants. Seed development is completed in 30d in LD while it takes 40d in SD, though the seed weights are similar. The maximum rate of fresh-weight gain of all the growing seeds of eight fruits on a plant in SD (1,440 mg/d) does not reach the maximum rate of weight gain of a similar fruit complement in LD (1,720 mg/d). The appearance of senescence symptoms in the shoot apices of LD-grown G2 plants occurs, however, prior to the time of the greatest rate of seed-weight gain. In LD, four fruits with a combined maximum growth rate of 1,250 mg/d are sufficient to cause the appearance of senescence symptoms. This is a lower combined seed growth rate than in SD where senescence does not occur. The seeds in up to 12 fruits can be growing at any time in SD with a combined maximum seed-growth rate (1,660 mg/d), only slightly less than the maximum in LD, with no sign of senescence. It is concluded that the different rates of seed growth occasioned by different photoperiods bear no relation to senescence. However, photoperiod does alter the spatial relationship of the shoot apex and the filling fruits. In LD apical growth becomes slower as fruiting proceeds so that the distance between the filling fruits and the apex is decreased to only two nodes while in SD, because of the delayed fruit development compared to LD, the spatial separation between the fruits and the shoot apex is nine nodes. Even if the growth rate of the plant had remained constant in LD it is calculated that an equivalent fruit complement would still be located three nodes further from the apex in SD than in LD. This increased spatial separation of fruits and apex in SD compared to LD probably alters the source/sink distribution of photosynthate and leaf derived hormones so that larger amounts are available to the apex in SD than LD. Also any senescence factor exported from fruits is less likely to reach the apex in SD. In continuously deflorated plants of G2 the two uppermost expanded stipules enclose the apex in SD while in LD they open out. The effect is reversible. Thus photoperiod probably affects the apex and its growth, directly, i.e. independent of fruit development, and this is accentuated by the differing spatial relationships of the apex and fruits resulting from different fruit growth rates under the different photoperiodic conditions.Abbreviations LD long day(s) - SD short day(s)  相似文献   

18.
Summary The likelihood that a plant's seeds will be dispersed by fruit-eating birds may depend upon the size and shape of its fruits. Assuming that elongate fruits can be swallowed more easily than spherical fruits of equal volume and that plant fitness is enhanced by seed dispersal by many individuals and species of birds, natural selection should favour increasing fruit elongation with increasing fruit size in bird-dispersed plants. According to this view, this allometric pattern would be adaptive. Alternatively, fruit shape in bird-dispersed plants may be constrained by development or phylogeny. To determine whether there was any evidence to support the adaptive allometry hypothesis, we examined allometric relationships between length and diameter in fruits and seeds in a group of neotropical bird-dispersed plant species. Using the major axis technique, we regressed ln(diameter) on ln(length) for fruits and seeds at various taxonomic levels: (1) within individual trees ofOcotea tenera (Lauraceae) (2) among 19 trees within a population ofO. tenera, as well as among pooled fruits from multiple trees within 20 other species in the Lauraceae, (3) among 25 sympatric species within a plant family (Lauraceae) and (4) among 167 species representing 63 angiosperm families within a plant community in Monteverde, Costa Rica. At most taxonomic levels, a tendency for fruit length to increase more rapidly than fruit diameter among fruits (negative allometry) occurred more frequently than expected by chance. Estimated slopes of the regressions of fruit length on fruit diameter were < 1 within 15 of the 19 individualO. tenera trees, among tree means withinO. tenera, among pooled fruits within 16 of the 20 other species in the Lauraceae, among species means within the Lauraceae and among means of all bird-dispersed species in the lower montane forests of Monteverde. Seed allometry showed similar patterns, although for both fruits and seeds the broad confidence intervals of the slopes estimated by major axis regression overlapped 1 in many cases. Among the 63 Monteverde family means, fruit length and diameter scaled isometrically. Based on measurements of ontogenetic changes in fruit shape in a single species,O. viridifolia, we found no evidence that negative allometry in fruit shape within the Lauraceae was an inevitable consequence of developmental constraints. Instead, increasing elongation of fruits and seeds in certain plant taxa is consistent with adaptation to gape-limited avian seed dispersers. Contrary results from vertebrate-dispersed species from Malawi and Spain may reflect differences between the New and Old World in plant taxa, seed dispersers or evolutionary history.  相似文献   

19.
Zornia subsessilis, a new species from Serra do Cabral, Minas Gerais State, Brazil, is described and illustrated on the basis of field and herbarium studies. It belongs to Zornia section Zornia of subgenus Zornia and it appears to be restricted to “campo rupestre” (rocky fields) within the “cerrado” biome. This new species is characterized by its sessile to subsessile leaves, fruits with articles 4 to 5 mm long and with bristles up to 3.5 mm long.  相似文献   

20.
Summary We investigated inter-specific variation in fruit characteristics — fruit size, seed number per fruit, seed weight, nutritional content, fruit persistence, and fruit synchronization — in relation to flowering and fruiting phenology in 34 species of fleshy fruited plants. Except for aspects of fruit synchrony and persistence, the results in general were inconsistent with previous suggestions about adaptive variation in phenologically related fruit traits. The main results were as follows: (1) Late flowering, late fruiting, lengthy development time from flower to fruit, and highly persistent fruits constitute a complex of correlated characteristics among the species. (2) Synchronization of fruiting within individuals increased from early ripening fruits to late ripening fruits. Fruiting synchrony was more pronounced in species with a small crop size than in species with a large fruit crop, whereas synchrony was not significantly related to flowering synchronization, nor to life form. (3) Nitrogen and carbohydrate content of fruit pulp did not vary in relation to phenology, whereas lipid content decreased from early to late ripening fruits. (4) No seasonal trends were found for variation in seed size or seed number per fruit. (5) Interactions with flowering phenology and developmental constraints are important in phenological fruiting patterns. Temporal variation in start of fruiting was partly (36%) explained by variation in flowering time. Seed weight variation explained 17% of variation in development time from flower to fruit. (6) Despite constraints from flowering and seed development, some adaptive adjustment in fruiting phenology is likely to be allowed for among the investigated species. Such an adaptive variation in fruiting phenology was suggested by intra-generic comparisons of Prunus and Vaccinium species.  相似文献   

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