苦草属植物雄花果实种子显微结构的研究

苦草属植物体外部形态相似,叶线行或带形,野外难以直接鉴定到种,而雄花雄蕊数目、果实和种子的显微结构是苦草属(Vallisneria)植物物种的鉴别性特征之一。苦草属物种的雄花小,仅有1.5 mm,人工解剖雄花观察方法难以实现雄花雄蕊数目的识别;本研究采用雄株雄佛焰苞水培预培养技术获取自然开放的雄花并利用解剖学显微镜对3种苦草属植物雄花、果实和种子进行了解剖观察和研究。显微结构观察表明,苦草(V. natans)雄蕊1枚,果实圆柱形,表面光滑,种子无翅,具纵条纹;刺苦草(V. spinulosa)雄蕊2枚,果实三棱形,棱上具刺,种子具翅;密刺苦草(V. denseserrulata)雄蕊2枚,果实三棱圆柱形,表面光滑,种子无翅。依据文献,密刺苦草、刺苦草、长梗苦草(V. longipedunculata)和安徽苦草(V. anhuiensis)是安徽苦草属新分布记录种,其中长梗苦草和安徽苦草是分布于安徽的新种。     

长梗苦草雄花结构的环境扫描电镜观察

用环境扫描电子显微镜对沉水植物长梗苦草(Vallisneria longipedunculata)的雄花结构进行了观察研究。结果显示,长梗苦草雄花具3枚花被,2枚雄蕊是由3枚雄蕊中的1枚退化而来的,退化雄蕊清晰可见;花药4室,发育过程中通过药室顶端开裂,以及花药室基部的细胞收缩,将花粉粒都推到花药室的裂口处进行发育,成熟花粉粒直接外露;长梗苦草的花粉粒直径约50μm,壁薄,表面几乎没有纹饰,未发现萌发孔或萌发沟,这些是对特殊生境和传粉方式的适应。     

长江中下游湖泊两种混生苦草属植物生活史特征与共存分布格局

 在对长江中下游流域湖南、湖北、江西和安徽4省25个湖泊苦草属(Vallisneria)植物种群进行广泛的取样调查、鉴定和查明种间共存格局的基 础上,结合同园种植实验,对该属两个混生近缘种刺苦草(V. spinulosa)和苦草(V. natans)有性和无性生活史特征进行了定量测定和比较研究 ,探讨了种间生活史差异对种间共存格局的影响。结果表明：1)刺苦草是长江中下游湖泊的优势物种,苦草为常见种,而密刺苦草(V. denseserrulata)仅有很少分布;2)苦草和刺苦草常混生于这些湖泊中,形成共存分布格局：刺苦草和苦草种间呈明显的的带状相间分布格局, 或苦草只零星分布于刺苦草群落中;3)刺苦草和苦草有性和无性生活史特征显著不同：刺苦草为多年生,主要以无性繁殖为主,只有有限的有 性繁殖投入;相反,苦草在调查的地区为一年生,以有性繁殖为主,只进行微弱的克隆生长,且不能产生克隆繁殖器官(冬芽)。刺苦草和苦草 在有性和无性繁殖生活史对策上的权衡,导致种间资源利用和竞争能力的分异而使这两个近缘种得以共存。     

中国苦草属(Vallisneria)植物命名考及区分要点

由于苦草属（Vallisneria L.）植物的繁殖器官微小,营养器官相似且变异较大,使该属植物的鉴定和命名较混乱。笔者通过对有关文献的考证和长期跟踪观察,对我国记载的苦草属3种植物——苦草（Vallisneria natans（Lour.）Hara）、刺苦草（V.spinulosa Yan）、密刺苦草（V.denseserrulata Makino）的命名历史进行了梳理,并对这3种植物的形态特征进行了详细描述。根据种间形态差异,可为苦草属植物的分类鉴定和相关研究提供一定的参考。     

亚洲苦草与刺苦草的染色体数目和核型

本文以亚洲苦草和刺苦草根尖为实验材料,对其染色体数目及核型进行了研究,结果表明,两个种均为2n=20,同属Stebbins的不对称核型,亚洲苦草为“3B”,刺苦草为“2B”。核型公式分别为:K(2n)=20=2m+12sm+6st,K(2n)=20=2M+2m+14sm+2st。     

我国苦草属(Vallisneria L.)植物的生态学研究

苦草是水鳖科(Hydrocharitaceae)苦草属(Vallisneria)沉水草本植物,无直立茎,叶基生,线形或带形,常被称为扁担草、蓼萍草、水韭菜、面条草、扁子草和鸭舌条等,广泛分布于世界各地。本属植物有6～10种〔1,2〕,我国的苦草属植物依《中国植物志》第8卷有3种——苦草(V.natansHara)、刺苦草(V.spinulosaYan)和密刺苦草(V.denseserrulataMakino),而没有V.spiralisL.,VasiaticaMiki和V.giganteaGraebner等种〔1〕。本文苦草属植物的命名以《中国植物志》第8卷为准,引用文献一般尊重原作者的意见。下文中,无具体说明,苦草均为苦草属植物的通…     

药用观赏植物——贴梗海棠

贴梗海棠(Chaenomeles speciosa),别名铁脚梨、皱皮木瓜等,为蔷薇科多年生落叶灌木。株高2.3米,树皮褐色,平滑。枝外展,棕褐色。具明显的皮孔,有长刺。单叶互生或簇生,卵形至倒卵状椭圆形,边缘具密而细的锐锯齿。花先叶开放或与叶同放,数朵簇生,萼筒钟状,花瓣深红、淡红、白色,梨果卵球形或长圆形,外皮光滑,黄色或黄绿色,种子多数。花期3-4月,     

中国刺蕊草属(唇形科)植物一新记录种

报道了中国唇形科(Lamiaceae)刺蕊草属一新记录种--香薷状刺蕊草(Pogostemon elsholtzioides Benth.),该种在中国产于西藏墨脱县,凭证标本保存在PE。该种在喜马拉雅地区分布广泛,与特产于云南西北部地区的狭叶刺蕊草(P. dielsianus Dunn)的主要区别为：花萼钟形,长3~3.5 mm,花萼齿长为花萼筒的1/3~1/2,花冠长约4.5 mm。     

封面植物简介——庙台槭

庙台槭(Acer miaotaienseTsoong)属槭树科槭属,是我国植物学家钟补求先生1954年发现并命名的,模式产地在陕西省留坝县庙台子,故命名为庙台槭.该种为落叶乔木,高10~20(25)m;树皮深灰色,纵裂或片状剥落;幼枝红褐色或紫褐色,老枝灰色,深纵裂.叶对生,纸质,常3~5裂;轮廓近阔卵形或卵状三角形,长(4~)7~9cm,宽6~8cm;上面深绿色,无毛;下面淡绿色,被褐色短柔毛,沿脉较密;叶柄长6~7cm.圆锥状聚伞花序长4~5cm,生于枝顶,由1顶花及6~9枚侧花枝和14~25朵花组成;含两性花、雄花和中性花,同株.花黄绿色,直径约1cm;萼片5枚,长4.5~6.5cm,矩圆形或倒卵状长圆形,上、下表面均被短纤毛,下面较多;花瓣5枚,长3.5~4.5mm,倒披针形,较萼片窄短,上、下表面均有短纤毛,下面稍多;雄蕊8枚,花药黄色,近球形,花丝着生在花盘上;花盘近圆形,边缘波状5浅裂;雌蕊2心皮,扁平,柱头2裂,向外反卷.小坚果扁平,近圆形,直径约8毫米,密被淡褐色或黄色绒毛;翅长圆形,宽0.8~0.9cm,连同小坚果长约2~2.5(3)cm,两翅水平开展,呈180°平角,或有的大于180°....     

毛舞花姜花器官的发生与发育

通过扫描电镜观察了毛舞花姜(Globba barthei Gagne p.)的花序及花器官的发生与发育。3枚萼片原基首先于花顶连续发生,随后花顶的中心凹陷形成环状原基,环状原基进一步分化形成三枚花瓣—雄蕊共同原基,并在花顶的中心形成花杯。共同原基分化形成花瓣和三枚内轮雄蕊,紧接着外轮雄蕊在花杯的顶点发生。远轴的两枚内轮雄蕊延伸生长并相互融合形成了唇瓣,近轴的一枚形成了可育雄蕊;近轴的两枚外轮雄蕊发育形成了成熟花结构中的侧生退化雄蕊,而远轴的一枚缺失。近轴的两枚外轮雄蕊原基起始的同时,3枚心皮原基也在中心花杯的内侧发生而后与外轮雄蕊相间排列。对毛舞花姜花序的发生和发育的观察发现,在花序轴的头几片初级苞片中产生的是珠芽原基而非蝎尾状小花序原基,其形态特征类似于早期的蝎尾状小花序原基,由此推测珠芽很可能是蝎尾状小花序的变异。     

Petal herbivory by chrysomelid beetles (Phyllotreta sp.) is detrimental to pollination and seed production in Lepidium papilliferum (Brassicaceae)

Abstract.  1. Insect herbivory directed at flowers can decrease fruit and seed production by decreasing the attractiveness of a damaged flower to potential pollinators, by disrupting the transfer of pollen between pollinators and stigmas, or both.
2. Effects of petal herbivory by a chrysomelid beetle ( Phyllotreta sp.) on pollination and seed production in Lepidium papilliferum (Brassicaceae) were examined.
3. Under natural conditions, flowers with a hole chewed in a petal produced fruit and seed at a significantly lower rate than undamaged flowers (44% vs. 80% respectively). However, when damaged and undamaged flowers were hand pollinated, there was no significant difference in fruit or seed set (84% vs. 80% respectively).
4. Petal herbivory in L. papilliferum disrupts the effectiveness of insect-mediated pollination, but it does not physically inhibit pollination or seed production.     

The effect of petal size manipulation on pollinator/seed-predator mediated female reproductive success of Hibiscus moscheutos

The effects of petal-size manipulations on the behavior of pollinators and pollen/seed predators, and on pollen removal and deposition, were studied in Hibiscus moscheutos (Malvaceae) populations. The ultimate effects on the female reproductive success of flowers, such as fruit set, seed predation rate, and final seed set were also measured. We applied three levels of petal removal (100%, 50%, and 0% size reduction in radius) to flowers in natural populations. Two pollinators (Bombus pennsylvanicus and Ptilothrix bombiformis) ignored flowers without petals, suggesting that pollinators use petals as a visual cue to locate flowers. Consequently, 100% petal removal reduced female reproductive success considerably, mainly through a higher rate of fruit abortion due to failure of pollen deposition on stigmas. No significant differences between the 50% petal removal treatment and uncut control were detected in any components of female success examined. The results, therefore, suggest that differences in petal size have little influence on female reproductive success of Hibiscus flowers at our study site. Final seed set varied considerably depending on the larval densities of two coleopteran seed predators (Althaeus hibisci and Conotrachelus fissunguis). A. hibisci responded to petal size, and a higher density of adults was found in flowers in which petal size had not been reduced. Because Althaeus feed on pollen as adults and no effect of petal size on seed predation was detected, the preference of Althaeus for larger flowers may represent a foraging strategy for adult beetles and may exert counteracting selection pressure on petal size through male reproductive success of flowers. Received: 30 November 1997 / Accepted:12 June 1998     

几种水生植物种子萌发的聚集效应研究

以10种常见水生植物的种子为材料,研究了种子聚集对其萌发的影响。结果表明,水鳖科植物种子萌发对聚集的响应多为正效应：海菜花（Ottelia acuminata）、出水水菜花（O.emersa）、密刺苦草（Vallisneria denseser-rulata）、水鳖（Hydrocharis dubia）和无尾水筛（Blyxa aubertii）种子聚集后其最终萌发率显著提高;苦草（V.na-tans）和刺苦草（V.spinulosa）种子聚集后最终萌发率虽然没有显著提高,但是其萌发速率得到显著提高。种子聚集对穗花狐尾藻（Myriophyllum spicatum）的种子萌发有显著的抑制作用,而对穿叶眼子菜（Potamogeton perfo-liatus）和水麦冬（Triglochin palustre）的种子萌发无显著作用。水生植物的种子聚集萌发特性可能与其繁殖策略有关。水鳖科植物多进行有性繁殖或者有性繁殖比例较大,其种子也由于粘性物质的包裹为聚集分布,在野外聚集萌发的大量植株形成一个单一物种的斑块,这有利于迅速占领新生境。而穗花狐尾藻、穿叶眼子菜和水麦冬种群维持和扩张基本依靠克隆繁殖。     

Capparis dongvanensis sp. nov. (Capparaceae) from Vietnam

Capparis dongvanensis (Capparaceae) is described as a new species and illustrated from Ha Giang Province of Vietnam. It is morphologically similar to C. lanceolaris and C. fengii, but differs in the number of flowers on peduncles, length of spine and petiole, apex of the leaf, type of inflorescence, petal color, cylindrical ovary without any beak, fruit shape and number of seeds per fruit. Diagnostic morphological characters along with pollen and seed SEM images of C. dongvanensis and allied species are provided. Its ecology, habitat and conservation status are also described.     

Pollination biology and sexual differentiation ofOsyris alba (Santalaceae) in the Mediterranean region

Osyris alba L. is a widespread dioecious hemiparasitic shrub of S Europe, N Africa, and SW Asia. Male inflorescences are multiflowered whereas each female inflorescence is reduced to a single flower with persistent enlarged bracts. Pollination is a prerequisite for fruit and seed development and wind is unlikely to be an effective means of pollen spread. In southern Italy pollen is transported by small unspecialized flies and beetles. Both male and female flowers produce an indistinguishable sweet odour. Male flowers are produced in large numbers and over a larger period than the females and provide pollen, nectar, and staminal hairs as rewards for pollinators. The presence and function of staminal hairs with tip cells inOsyris alba has been reported for the first time. Female flowers are rewardless, producing neither mature pollen, nectar nor staminal hairs, but possess three modified yellow indehiscent anthers containing no viable pollen which may provide a strong visual feeding stimulus for pollinators. It is suggested that pollinators are attracted by deceit to female flowers by mimicry of the males and the floral mimicry is, therefore, intraspecific and intersexual. The floral characteristics and flowering phenology of male and female plants are consistent with this kind of mimicry. The female flower possesses a tricarpellary ovary with three ovules of which only one develops. The single seed, containing a small embryo and a large, rich endosperm, is borne in a red fleshy bird-dispersed fruit. The reduction in seed number per flower to one highly nutrient-invested seed, together with a reduction of the multiflowered inflorescence to a solitary flower and the sequential production of ripe fruits over an extended fruiting season, suggest that the female function is markedly resource-limited. It is suggested that, although all the reproductive characteristics present inOsyris alba, as well as hemiparasitism, had probably evolved before the end of the tropical Tertiary, they are of adaptive advantage in the nutrient and water-limited environment of the Mediterranean maquis.     

Micromorphological studies on Verbascum (Scrophulariaceae) in Iran with emphasis on seed surface, capsule ornamentation and trichomes

Seed micromorphology in 22 species, capsule surface in 28 species and capsule hairs in 20 species of genus Verbascum distributed in Iran were studied using scanning electron microscopy. The seed surface is ridged or alveolate among the studied species. Depth and density of the alveoli or ridges, size of polygonal cells along with arrangement of vesicles on the walls separating the polygonal cells on the seed surface seem to be species-specific in Verbascum. The capsule surface is striate, distinctly or indistinctly, or even smooth in Verbascum. The capsules are rarely glabrous (in V. orientale and V. intricatum), densely covered by branched hairs, or loosely by glandular hairs, depending on species. From the results of this study it is obvious that no correlation exists between the studied species concerning the micromorphological aspects studied here.