珍稀濒危植物单性木兰传粉生态学研究

野外定位观测了单性木兰的花期物候、访花昆虫种类、访花频率、访花行为和同花期植物种类,并对其花粉散播距离和繁育系统进行了检测,旨在探讨制约单性木兰传粉过程的某些因素,为单性木兰的保护生物学提供科学依据。结果表明,单性木兰雄株和雌株在花期物候上存在差异,雌株在结实上存在明显的大小年现象。单性木兰以虫媒传粉为主,雄株访花昆虫30种,雌株访花昆虫仅14种,雌株和雄株共有的访花昆虫仅6种。单性木兰同花期植物共17种,其访花昆虫种类大部分与单性木兰的访花昆虫种类相同。蜂类和蝶类均非单性木兰的传粉者,其结实率低的原因不仅与访花昆虫种类少和访花频率少有关,更与其缺乏有效的传粉昆虫有关。     

基部被子植物雪香兰（金粟兰科）单性花的形态发生和发育

基部被子植物金粟兰科（Chloranthaceae）的单性花或两性花结构十分简单,雪香兰（Hedyosmum orientale）花单性、雌雄异株,花的形态及结构与其它属物种具有显著的差异,对于研究被子植物花特别是花被的起源和系统进化具有重要意义。该研究采用电子显微镜和光学显微镜观察了雪香兰单性花的器官发生及发育过程。结果表明,雌、雄花均为顶生和腋生,多个小花呈聚伞圆锥状排列。雄花外侧是苞片,每朵雄花上着生150–200个雄蕊,花轴基部着生少数退化的叶原体。苞片原基及其腋生的花原基最初呈圆丘状,随后伸长。在雄花发育过程中,苞片原基比雄蕊原基生长快,雄花原基纵向伸长,叶原体原基在基部发生,雄蕊原基自下而上发生。每2朵雌花底部合生形成小聚伞花序,每朵雌花被一苞叶包裹,由单心皮和三棱型子房构成,外覆三裂叶状花被。在雌花发育过程中,雌花原基比苞片原基生长快,花被原基首先于花顶端发生,随后花顶端中心凹陷,进一步发育成具有单心皮的子房原基。雪香兰的单性花发育不经过两性同体阶段,花分生组织只起始雄蕊器官或雌蕊器官的发育。研究结果支持雪香兰单性花是原始性状的观点,雄花叶原体与雌花三裂叶状花被同源,可能是花被（萼片与花瓣）的起源。     

峨眉拟单性木兰的开花生物学特性与繁育系统

为阐明峨眉拟单性木兰(Parakmeria omeiensis)在自然条件结实率低的原因和确定最佳人工授粉时期,该文通过观察峨眉拟单性木兰的开花动态,采用杂交指数估算、花粉胚珠比、花粉活力及柱头活性检测、人工授粉试验等方法对其繁育系统进行了研究。结果表明:(1)植物园保育的峨眉拟单性木兰花期在4月底到5月中下旬,持续17～23 d,雄株始花期比雌株早3～4 d,但两者花期可遇。(2)两性花经检测雄蕊败育,实为功能上的雌性,部分雄株个体的雄花上残留1～2个心皮,其性别分化是通过雌、雄蕊选择性败育形成的,为隐性雌雄异株(cryptic dioecy)。(3)雄花、两性花开放经历佛焰苞开裂、花被片开裂、展开、闭合、二次开放、凋落6个阶段,历时4 d。(4)雄花初次展开时花粉活力最高,达92.8%,开花2 d后活力显著下降;两性花柱头在花被片展开期可授性最强,盛开后柱头部分可授。(5)杂交指数为5,P/O比为2.14×10~4。(6)套袋试验表明,峨眉拟单性木兰不能进行自花传粉,人工异花授粉的结实率和出种数显著高于自然授粉,且不存在无融合生殖。这说明峨眉拟单性木兰繁育系统为专性异交,传粉过程需要传粉媒介,自然条件下结实率低,主要是受传粉昆虫和柱头可授期短的限制。     

单性木兰（木兰科）花的形态发生

报道了单性木兰(Kmeria septentrionalis Dandy)花的形态发生过程。发现过去一直被认为是雌花条状披针形的“内轮花被片”,实际为退化雄蕊,它形态发生的时间与位置均与雄花的雄蕊相同,在成熟结构中仍可见药室残迹,说明单性木兰的雌性花是由两性花退化而来。通过与K. duperreana(Pierre) Dandy和Magnolia thailandica Noot. &; Chalermglin雌花的比较,发现它们雌花的形态相同,从而得知人们长期以来对此3种植物雌花的认识有误,原一直认为的“内轮花被片”实为退化雄蕊。     

珍稀濒危植物小花木兰传粉生物学研究

基于定株观测,对小花木兰（Magnolia sieboldii）野生种群和人工栽培种的开花物候进行了研究。结果表明,小花木兰花期为5月中下旬至6月中下旬,花期20d左右,单花花期一般为5～7d,盛花期为6月1～5日;开花过程中花部表型变化明显,花粉在花开时不成熟,但雌蕊已经成熟,花开后雌蕊柄伸长,约20h后下柱头依然湿润,上柱头已萎缩变褐色,再过约40h下柱头也萎缩失去活力．此时花粉成熟,花药裂开;花的柱头接受到的花粉量由下往上依次减少。检测花粉活力、萌发率发现,小花木兰花粉在散发6d后基本失去活力和萌发能力。重力玻片法观测表明,小花木兰为虫媒传粉;花柱的授粉率不高,为65％;柱头上平均花粉量为3．5个;自然状态下结实率低,为13．5％,人工栽培为20．1％;外轮花被片全部去掉,结果率下降至11．3％;去掉雄蕊,结实率下降至10．7％;再辅以人工授粉,结果率上升至25．0％。小花木兰的访花昆虫种类较少,访花频率低,其中蜜蜂和一种蚜科（Aphididae）小昆虫对其传粉影响较大。同花期灯台附（Cornus controversa）等植物对其传粉产生昆虫竞争作用。环境因素如光照、温度、阴雨、海拔等均对其传粉产生一定影响。     

焕镛木属——中国木兰科一新属

焕镛木属(Woonyoungia Law)曾分布于广西西北部罗城县,现星散分布于广西北部环江县,贵州省东部荔坡县、云南西南部马关县、是珍稀濒危树种。焕镛木属的花单性异株,与木兰科其他各属均不同;雄花的花被片形态相似而雌花的花被片则明显异形,这也是与木兰科其他各属均不同。此外,焕镛木属的雄蕊两药室稍分开,内侧向开裂,药隔伸出成舌状尖;雌蕊6-9,心皮全部合生,仅露出柱关面;成熟心皮革质,沿背缝开裂,形成近球形的聚合果。与它近缘的单性木兰属(Kmeria Dandy)则雄蕊两药室紧贴,内向开裂,顶端钝,药隔不伸出;成熟心皮木质、沿腹缝全裂及顶端开裂,最后裂成两果瓣、形成各成熟心皮散开的聚合果等不同。依上述不相同特征,故成立焕镛木属属新属。     

Differences in floral traits and flower visitation rates in mating systems in Prunella vulgaris (Lamiaceae)

夏枯草交配系统对花特征和访花频率差异的影响 植物花特征和传粉者的访问次数与交配系统类型密切相关。唇形科植物夏枯草(Prunella vulgaris)存 在两种植株类型,分别为柱头伸出花冠和柱头在花冠内部的植株,而且两种植株的比例在不同种群中存在差异。本研究选择柱头伸出花冠外植株占绝大多数、柱头伸出花冠外植株占多数和柱头在花冠内部植株占多数的3个种群,通过比较每个种群中两种植株类型的开花物候、花形态特征、昆虫访问频率、自交能力、传粉者对结实的贡献以及近交衰退的水平,以检验花特征和传粉者访问次数与交配系统类型的关系。研究结果表明,与柱头在花冠内部的植株相比,柱头伸出花冠外的植株具有更大和更多的花,产生更多的花粉和花蜜,具有更高的访花频率,并主要通过异交产生种子。在种群水平,柱头伸出花冠外的植株占多数种群的访花频率显著高于柱头在花冠内部植株占多数的访花频率。柱头在花冠内部的植株比柱头伸出花冠外的植株具有更强的自动自交能力,在传粉者缺乏时为其提供了繁殖保障,但繁殖保障和异交率在不同种群中差异不显著,表明较低的昆虫访问能够满足夏枯草的授粉需求以产生种子,这可能与夏枯草较少的胚珠数量(每朵花仅有4个胚珠)有关。柱头在花冠内部植株的近交衰退水平低于柱头伸出花冠外植株的近交衰退水平,但两种植株类型的近交衰退水平均低于0.5,说明近交衰退不足以阻止该物种中自交的进化。综上所述,柱头在花冠内部的植株能够通过自交为夏枯草提供繁殖保障,而柱头伸出花冠外的植株能够利用昆虫传粉确保异交,表明混合交配系统在该物种中是一个稳定的状态。     

霉草科,缅甸被子植物一新记录科

在近期缅甸北部的植物考察中,一种菌类寄生植物矮生喜荫草(Sciaphila nana Blume)被发现和确认。矮生喜荫草代表缅甸被子植物一新记录科,霉草科植物。矮生喜荫草主要特征为花单性同株、雄花内轮花被片顶端具有柄的门把状物、花被片6、3个雄蕊、花药4室。     

霉草科,缅甸被子植物一新记录科（英文）

在近期缅甸北部的植物考察中,一种菌类寄生植物矮生喜荫草(Sciaphila nana Blume)被发现和确认。矮生喜荫草代表缅甸被子植物一新记录科,霉草科植物。矮生喜荫草主要特征为花单性同株、雄花内轮花被片顶端具有柄的门把状物、花被片6、3个雄蕊、花药4室。     

不同海拔圆叶天女花的传粉生物学研究

对国家Ⅱ级重点保护野生植物、准四川省特有植物和优先拯救保护的极小种群植物圆叶天女花[Oyama sinensis(Rehder et E.H.Wilson)N.H.Xia et C.Y.Wu]在不同海拔居群[P1(海拔1 758 m)、P2(海拔1 988 m)、P3(海拔2 181 m)和P4(海拔2 397 m)居群]的花部特征、花粉活力和柱头可授性进行了研究,并对其访花昆虫的种类和访花行为进行了观察。结果表明:P2和P3居群圆叶天女花的花朵直径、花被片长和花被片宽总体上显著(P0.05)大于P1和P4居群,而4个居群间花朵长的差异不显著(P0.05)。随着海拔升高,圆叶天女花在雄蕊和雌蕊投入上逐渐减少,其雄蕊、雌蕊、花粉和胚珠的数量以及花粉/胚珠比(P/O)总体上呈逐渐减小的趋势。高海拔居群(P3和P4居群)圆叶天女花的花粉活力和柱头可授性明显高于低海拔居群(P1和P2居群),雄蕊和雌蕊的寿命更长。熊蜂(Bombus ningpoensis)、花蚊子(Aedes albopictus)、中华蜜蜂(Apis cerana)、食蚜蝇(Syrphus sp.)和白粉蝶(Pieris rapae)为圆叶天女花的有效传粉昆虫,其中,主要访花昆虫熊蜂的访问高峰期为10:00—14:00。P2和P3居群圆叶天女花花朵的展示效果较好,访花昆虫种类较多(10~11种)。随着海拔升高,圆叶天女花访花昆虫的访问次数逐渐减少。研究结果显示:随着海拔升高,延长花粉和柱头的寿命为圆叶天女花提高传粉效率和增强适应性的有效策略。     

Anatomy and ontogeny of unisexual flowers in dioecious Woonyoungia septentrionalis （Dandy） Law （Magnoliaceae）

Woonyoungia septentrionalis （Dandy） Law is aceae. The floral morphology and structure of the species a dioecious species with unisexual flowers in Magnoliare conspicuously different from other species and are important to the study of floral phylogeny in this family. The floral anatomy and ontogeny were investigated to evaluate the systematic position of W. septentrionalis, using scanning electron microscopy and light microscopy. All of the floral organs are initiated acropetally and spirally. The carpels are of conduplicated type without the differentiation of stigma and style. The degenerated stamens in the female flowers have the same structures as the normal stamens at the earlier developmental stages, but they do not undergo successive development and eventually degenerate. The male floral apex was observed to have the remnants of carpels in a few investigated samples. As the bisexual flower features could be traced both in the male and female flowers in W. septentrionalis, it suggests that the flower sex in Magnoliaceae tends toward unisexual. As well as the unisexual flowers, the reduced tepals and carpels and concrescence of carpels conform to the specialized tendency in Magnoliaceae, which confirms the derived position of W. septentrionalis in this family. As the initiation pattern of floral parts of W. septentrionalis is very similar to other species in this family, it needs further investigation and especially comparison with species in Kmeria to evaluate the separation of Woonyoungia.     

Bee boys and fly girls: Do pollinators prefer male or female umbels in protandrous parsnip,Trachymene incisa (Apiaceae)?

Abstract Complete dichogamy occurs when temporal separation prevents any overlap in male and female function within and among flowers of one or more inflorescences. Although dichogamy may increase outcrossing and prevent inbreeding, it also results in the presentation of inflorescences with different floral resources. Pollinators may prefer one gender over the other based on these differences, which can reduce the transfer of pollen to conspecific stigmas and reduce floral resources for effective pollinators. We investigated whether the insect visitors of Trachymene incisa (Apiaceae), an Australian herb demonstrating complete protandry at the umbel level, show a preference for male or female umbels. The male phase umbels present pollen and nectar, whereas the female phase umbels offer nectar only. Therefore, we expect pollen‐collecting insects to favour male umbels, whereas insects that forage only for nectar will favour female umbels. In natural patches that exhibited a male umbel bias, insects showed a preference for male phase umbels at Agnes Banks in 2003 and at Myall Lakes in both 2003 and 2004. By contrast, insects showed no preference for umbel phases, visiting umbels at a similar frequency to which they occurred, at Agnes Banks in 2004 and at Tomago in both 2003 and 2004. This suggests spatial and temporal variation in insect preferences for umbel phases that differ in floral rewards. In experimental arrays where the umbel gender ratio was equal, there were no significant differences between male and female umbels in terms of insect visitation during a foraging trip and mean foraging time per visit. The differing patterns of preference may be due to a differential response by insects when the umbel ratios vary, where a male bias in umbel genders leads to a preference for male umbels, whereas an equal umbel gender ratio leads to equal visitation to male and female phase umbels.     

独叶草的不育雄蕊、花被片和可育雄蕊对传粉昆虫和传粉的影响

为确定独叶草（Kingdonia uniflora）不育雄蕊、花被片和可育雄蕊对传粉昆虫和传粉的影响,分别进行去除不育雄蕊（A组）,去除花被片（B组）,去除可育雄蕊（C组）和对照组（D组）处理。结果表明：昆虫访花频率分别为A组0．4次／h、B组0次／h、C组0．9次／h、D组2．2次／h;被授粉花朵百分比分别为A组29．09％、B组40．38％、C组70.91％、D组91．67％;被授粉心皮百分比分别为A组17．77％、B组20．94％、C组为40．58％、D组为75．27％。与对照组相比,处理后被授粉花朵百分比、被授粉心皮百分比下降幅度均为A组〉B组〉C组。结合昆虫访花频率与不育雄蕊蜜汁的分泌量呈正比,可确定不育雄蕊产生的蜜汁是吸引昆虫访花的最主要因素。花被片为昆虫取食提供停歇的平台,可育雄蕊与花被片产生的色差及可育雄蕊提供的花粉,是吸引昆虫的辅助因素。     

Floral Variation in Tepals,Sterile and Fertile Stamens of Kingdonia uniflora (Ranunculaceae) with Reference to Pollinators and Pollination

To understand the influence of different floral organs of Kingdonia uniflora to the pollinators and pollination, we divided the flowers into four groups, A, with the sterile stamens removed, B, with the tepals removed, C, with the fertile　stamens removed and D, without the remove of any organ. The results showed that the insects visiting frequency were 0.4 time h in group A, 0 time h in group B, 0. 9 time h in group C and 2. 2 time h in group D. The percentage of pollinated flowers was 29.09% in group A, 40. 38% in group B, 70.91% in group C and 91. 67% in group D. The percentage of pollinated carpels was 17.77% in group A, 20.94% in group B, 40.58% in group C and 75.27% in group D respectively. The relationships between the insect visiting frequency and the nectarial secretion of the sterile stamens were observed in the field. To compare with group D, the decrease of the rate of pollinated flower and the carpel was group A > group B>group C. To combine the observation of the relationships between the nectarial secretion of the sterile stamens and the insect visiting frequency, we considered that the sterile stamens with nectar as the reward of the visiting insects play the most important rule for the pollinators and pollination. However, the tepals that could afford the platform of staining and moving of the insects on the flowers are also important for the pollinators. The fertile stamens that could form the chromatic to attract some of the pollinators and supply the pollen grains as the food of some pollinators play less important rule .     

Pollination of Kadsura longipedunculata (Schisandraceae), a monoecious basal angiosperm, by female, pollen-eating Megommata sp. (Cecidomyiidae: Diptera) in China

The plants of Kadsura longipedunculata (Schisandraceae) are monoecious and possess either red or yellow male flowers (the androecium), with yellow tepals, and yellow female flowers. All flower types simultaneously produce heat and floral odours (dominated by methyl butyrate) throughout a 4–5-h nocturnal period. The flowers are pollinated only by female, pollen-eating Megommata sp. (Cecidomyiidae). Pollen is the only reward, and female flowers use the same attractants as male flowers but offer no food (pollination by deceit). Open pollinated flowers in nature varied in fruit set from 8 to 92%. Megommata (subfamily Cecidomyiinae, supertribe Cecidomyiidi), consists of six described species, which feed on Coccoidea (scale insects) and are distributed worldwide.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 523–536.     

Pollination of Schisandra henryi (Schisandraceae) by female, pollen-eating Megommata species (Cecidomyiidae, Diptera) in south-central China

BACKGROUND AND AIMS: The mutualistic interaction between insects and flowers is considered to be a major factor in the early evolution of flowering plants. The Schisandraceae were, until now, the only family in the ANITA group lacking information on pollination biology in natural ecosystems. Thus, the objective of this research was to document the pollination biology and breeding system of Schisandra henryi. METHODS: Field observations were conducted in three populations of S. henryi and the floral phenology, floral characters and insect activities were recorded. Floral fragrances were sampled in the field and analysed using TCT-GC-MS. Floral thermogenesis was measured with a TR-71U Thermo Recorder. Pollen loads and location of pollen grains on insect bodies (including the gut) were checked with a scanning electron microscope and under a light microscope. KEY RESULTS: Schisandra henryi is strictly dioecious. Male flowers are similar to female flowers in colour, shape, and size, but more abundant than female flowers. The distance between tepals and the androecium or gynoecium is narrow. Neither male nor female flowers are fragrant or thermogenic. Schisandra henryi is pollinated only by adult female Megommata sp. (Cecidomyiidae, Diptera) that eat the pollen grains as extra nutrition for ovary maturation and ovipositing. Both male and female flowers attract the pollinators using similar visual cues and thus the female flowers use deceit as they offer no food. CONCLUSIONS: Schisandra henryi exhibits a specialized pollination system, which differs from the generalized pollination system documented in other ANITA members. Pollen is the sole food resource for Megommata sp. and the female flowers of S. henryi attract pollinators by deceit. This is the first report of predacious gall midges utilizing pollen grains as a food source. The lack of floral thermogenesis and floral odours further enforces the visual cues by reducing attractants for other potential pollinators.     

异型花柱植物喀什补血草的传粉者功能群与花粉转移效率

异型花柱是受遗传控制的花柱多态现象, 被达尔文认为是植物通过在传粉者体表不同部位滞落花粉以促进型间花粉准确传递的一种适应。该现象虽已受到广泛关注, 但在一些花型变异较大且不稳定的传粉系统中, 不同传粉者对各花型繁殖所产生的影响仍知之甚少。该研究以分布于新疆天山南坡的一个有同长花柱共存的异型花柱植物喀什补血草(Limonium kaschgaricum)种群为研究对象, 对其花型构成及频率、传粉者及花粉转移效率等进行了调查分析。结果表明: 1)种群中除了存在雌/雄蕊长度交互对应的长(L)/短(S)花柱型花外, 还有雌/雄蕊同长的花(H型), 且各花型花的花冠口直径、花冠筒长及花粉量等参数间无差异, 但花粉纹饰和柱头乳突细胞形态具二型性。其中, H型花的花粉和柱头形态与L型花(或S型花)的一致。2)花型内和自花授粉均不亲和; 型间授粉时, 花粉和柱头形态不同的花型间亲和, 反之不亲和。3)种群内存在长/短吻两类传粉昆虫。在以短吻传粉者为主的盛花初、中期, L和H型花柱头上的异型花粉数均显著高于S型花的, 且L和S型花高位性器官间的异型花粉传递效率高于低位性器官间的; 而在以长吻传粉者为主的盛花后期, L和S型花的柱头间异型花粉数无显著差异, 且高/低位性器官间具有相同的异型花粉转移效率; 与传粉者出现时期相对应的、在花期不同阶段开放花的结实率也明显不同。4)长/短吻昆虫具明显不同的传粉功能, 短吻昆虫只能对L和H型花进行有效传粉, 且访花频率和型间花粉转移效率较低, 为低效传粉者; 而长吻昆虫对各花型均能有效传粉, 具高的访花频率和型间花粉转移效率, 为高效传粉者。因为长吻昆虫的阶段性出现所形成的不稳定传粉系统, 使低效的短吻昆虫可能会成为种群中花型变异的驱动力, 并使S型花受到更大的选择压力。H型花克服了柱头缩入的弊端, 可能会成为不稳定传粉系统下的一个替代花型而持续存在。     

柴黄姜的传粉生物学特性

对产自湖北武当山的柴黄姜（Dioscorea nipponica subsp．rosthornii Prain et Burkill）的花部特征和访花昆虫种类及访花行为、访花频率和携粉量进行了研究,并对柴黄姜的传粉方式、结实和种子萌发状况进行了检测。结果表明,柴黄姜具有虫媒花的典型花部特征,共观测到访花昆虫4目34种,其中传粉昆虫6种,隧蜂属（Halictus sp．）和地蜂属（Andrena sp．）的2种昆虫是柴黄姜的主要传粉昆虫。访花昆虫对雄株的访花高峰时段为11：00至14：00,对雌花没有明显的访花高峰时段。在自然条件下,柴黄姜的座果率为18．86％,结实率为7．12％,种子萌发率为64．76％。在武当山,柴黄姜种群扩展仍以有性繁殖为主,无性繁殖为重要补充。