Crossing and selfing experiments in theOrnithogalum umbellatum/augustifolium complex

The fertility relationships ofOrnithogalum umbellatum, O. angustifolium and 9 related taxa were studied.O. umbellatum andO. angustifolium, which are not interfertile, are both recognized as a comparium. Pollination of five species belonging to theO. umbellatum/angustifolium polyploid complex, i.e.O. umbellatum, O. angustifolium, O. baeticum, O. monticolum andO. algeriense, resulted in a moderate seed set. However, the seeds obtained after these interspecific crosses did not germinate. Six related species, i.e.O. exscapum, O. nivale, O. comosum, O. collinum, O. gussonei andO. woronowii showed a very low seed set after being crossed. One exception occurs:O. nivale ×O. exscapum. The seed set was also low after the complex species had been crossed with some related species, but there was one exception: both reciprocal crosses betweenO. monticolum andO. woronowii yielded some viable seeds. No other interspecific crosses gave rise to viable seeds. Bulbil-producing species have a lower seed set after self-pollination than species which do not produce bulbils.Biosystematic Studies on theOrnithogalum umbellatum/angustifolium Complex IV.—Previous contributions: (I–III):Raamsdonk (1982, 1985a, 1985b).     

Pollination ofOpuntia lindheimeri and related species

The large, yellow, bowl-shaped flowers ofOpuntia lindheimeri, O. discata, O. phaeacantha major, andO. compressa in Texas are visited by various species of beetles and bees. The beetles and small bees (Perdita, Dialictus) are pollen thieves. The pollinators are the medium-sized and larger bees (Melissodes, Diadasia, Lithurge, Megachile, Agapostemon, etc.). Different species of theOpuntia lindheimeri group have the same pollination system and there is no evidence of any floral isolation between them. The pollination system of these species ofOpuntia in Texas is essentially the same as that ofEchinocereus fasciculatus andFerocactus wislizeni in Arizona.Pollination of North American Cacti, II.—SeeGrant & Grant (1979).     

Pollen diameter and fertility in nine species ofPuccinellia (Poaceae)

Diameter and fertility of pollen grains were surveyed in nine species ofPuccinellia Parl. (Poaceae), mainly from the Iberian Peninsula, allowing information about reproductive behaviour and biological characteristics of pollen of these taxa. Maximum diameter was measured with an image processor and fertility was evaluated by staining the grains with Müntzing's mixture. Significant differences in both characters were found between the taxa. In consequence, maximum diameter and fertility proved to have some taxonomic relevance inPuccinellia.     

Selfing inNarthecium ossifragum (Melanthiaceae)

Hagerup's (1950) observations of rain pollination inNarthecium ossifragum are commonly admitted. Nevertheless,Daumann (1970) stated that pollen and stigmas suffer considerable damage from rain impact. Experimental pollinations and pollen observations were conducted at a single site in the Upper Ardennes, Belgium, during three years. Rain water had a deleterious effect on both fruit and seed set and on pollen germination. Fruit and seed set differed among years mainly due to rainy weather. Fruit set also varied among experimental treatments. Pollination trials showed thatNarthecium ossifragum is self-compatible and autofertile. Emasculation had a deleterious effect and caging had no effect on fertility.     

Pollen morphology ofLactoridaceae

The pollen wall ultrastructure of the primitive AngiospermLactoris fernandeziana Phil. (Lactoridaceae) is described. The monosulcate aperture, granular wall structure and sacci (all primitive features) suggest placement of this family in theMagnoliales. Pollen ofLactoris is compared to fossil dispersed pollen from the Lower and lower-Upper Cretaceous. The fossil pollen shares characteristics which are restricted to theLactoridaceae suggesting that this family was present during the early Cretaceous.     

Female reproductive development and pollen tube growth in diploid genotypes of<Emphasis Type="Italic"> Solanum cardiophyllum</Emphasis> Lindl.

We have characterized female gametophyte (megagametophyte) development and the kinetics of pollen tube growth in self-pollinated diploid genotypes (2n=2x=24) of Solanum cardiophyllum Lindl. that show normal seed formation. In this species megasporogenesis and megagametogenesis give rise to a female gametophyte of the Polygonum type composed of two synergids, an egg cell, a binucleated central cell and three antipodals; however, asynchronous abnormalities resembling mechanisms that prevail during the formation of second division restitution gametes were observed. In self-pollinated pistils at least 1–2% of germinating pollen tubes were able to reach the megagametophyte 60–84 hours after pollination (hap). Although the egg cell acquired a zygote-like morphology 60–84 hap, division of the primary endosperm nucleus was only observed 84 hap. The analysis of genetic variability in full-sib progeny confirmed that seeds are derived from sexual reproduction. These observations suggest that diploid genotypes of S. cardiophyllum can serve as an ideal system to genetically investigate true seed formation in a tuber-bearing Solanum species.     

An analysis of interspecific hybrids and phylogenetic implications inCucumis (Cucurbitaceae)

Investigations on interspecific crossability in 8Cucumis species (2n = 24) and chromosome pairing and pollen fertility of their hybrids from 15 combinations have been utilized for tracing the phylogenetic relationships among these taxa and factors responsible for their differentiation. A collective evaluation of data suggests that there are three broad groups of species, one of the spiny fruited interfertile species, whose hybrids show varying degree of chromosome associations and low to high pollen fertility; the second of species with non-spiny fruits, which are completely incompatible with the former but weakly compatible with the cultivated species,C. melo L. to produce partly developed seeds, and the third group ofC. metuliferus E. Mey. exSchrad. andC. melo and its different botanical varieties. The species with spiny fruits can be further divided based on karyomorphological similarities and/or on relative genomic affinity, indicated by chromosome pairing and hybrid pollen fertility.Cytogenetics inCucumis III.     

Pollination ofNuphar (Nymphaeaceae) in Europe: Flies and bees rather thanDonacia beetles

Nuphar (Nymphaeaceae) comprises a small holarctic group of aquatic perennials whose flowers are pollinated by flies, bees, and beetles. We studied pollination in different populations of the two European speciesN. lutea andN. pumila in Norway and in Germany. Flowers are self-compatible and protogynous, preventing automatic selfing, and insect pollination is required for seed production. Sympatric populations were studied in Vest-Agder county in Norway to determine whetherN. lutea andN. pumila have the same or different pollinators. Allopatric populations ofN. lutea in Germany and Norway were then compared to determine whether their pollinator spectra differ as would be expected in an open flower with seemingly easily accessible pollen and nectar. Results of the present as well as previous studies of the pollination ofN. lutea andN. pumila show that both species are mainly pollinated by flies, including apparentNuphar specialists, such as the scatophagidHydromyza livens and the ephydridsHydrellia andNotiphila, the last also a long-known pollinator ofN. advena in Florida. Pollinator overlap between sympatric heterospecific populations was small, while allopatric conspecific populations had similar visitor and pollinator spectra. We found no evidence of pollination byDonacia beetles as reported from some North American populations ofNuphar. Dedicated to Univ.-Prof. DrF. Ehrendorfer on the occasion of his 70th birthday     

Cytogenetical changes of offsprings from the induced tetraploid hybrid betweenRanunculus silerifolius (2n = 16) andR. chinensis (2n = 16) (Ranunculaceae)

Cytogenetical studies were carried out on the successive generations of offsprings from the induced tetraploid hybrid (2n = 32) betweenRanunculus silerifolius (2n = 16) andR. chinensis (2n = 16). Aneuploids, 2n = 30 to 35, frequently occurred. In latter subsequent generations the deviation of aneuploids increased, but the proportion of euploids decreased, accompanied by the reduction of fertility of pollen grains and seed sets. F₂ and F₄ PMCs constantly exhibited meiotic abnormality, i.e. formation of quadrivalents and univalents. The speciation process ofR. cantoniensis (2n = 32), which was presumed to arise from tetraploid hybrids between the above two species, is discussed on the basis of the above evidences.Former contributions of this series areOkada & Tamura (1977) andOkada (1984).     

A biometric study of theOrnithogalum umbellatum (Hyacinthaceae) complex in France

Macromorphological variation within theOrnithogalum umbellatum L. (Hyacinthaceae) complex in France was studied. The resulting data were treated by numerical taxonomy methods. Three morphs can be identified: one corresponding to diploid plants, another made up of triploids and a third which encompasses plants having ploidy level above 3x (4x, 5x, and 6x). A systematic interpretation of the complex is proposed wherein only one species,O. umbellatum, is retained. This species corresponds to a polyploid complex undergoing evolution.     

The pollination biology ofHibbertia stricta (Dilleniaceae)

The exines of pollen grains ofHibbertia stricta (DC.)R. Br. exF. Muell. (Sect.Pleurandra) wear an oily, yellow pollen coat that stains positively for lipids. The pollen is collected by asocial bees, exclusively. The most common floral foragers are members of the genusLasioglossum (subgenusChilalictus;Halictidae) and they harvest pollen via thoracic vibration. As these bees cling to the inflated anthers their pollen smeared bodies come in contact with either of the two wet, nonpapillate stigmas. The stigmas respond positively to cytochemical tests for the presence of esterase immediately following expansion of the corolla, indicating the effective pollination period. The foraging patterns of the bees are narrowly to broadly polylectic. AsH. stricta flowers are nectarless, it is not surprising that bees bearing mixed pollen loads always carry the pollen of at least one nectariferous, coblooming plant. The pollination biology ofH. stricta is compared with otherHibbertia spp. and with pollen flowers in general.     

Pollen grain morphology ofCoris (Primulaceae)

Pollen grain morphology, sculpturing, and wall ultrastructure are investigated in two species ofCoris (Primulaceae),C. monspeliensis L. andC. hispanica Lange. The study includes both acetolysed and unacetolysed pollen. No evidence of any major palynological difference is recorded between these two species, apart from a somewhat larger pollen inC. monspeliensis. However,Coris can be distinguished from the remaining members of thePrimulaceae by the conjunction of relatively large pollen grains, prominent margo, and particular tectal pattern causing a reticulate surface with minute luminal perforations decreasing towards the colpi. From both these distinctive features, and others typically primulaceous, some evolutionary considerations are inferred. Finally, the higher proportion of irregular grains inC. hispanica is interpreted in light of environmental stress.     

异叶苦竹花粉管生长及双受精过程

以异叶苦竹为材料,采用扫描电镜、荧光显微镜技术及传统的石蜡制片技术,解剖观察其花粉管生长途径及双受精过程。结果表明:(1)授粉后,花粉在柱头上吸水膨胀,约30 min即可萌发。(2)授粉1～2 h后花粉管可达到花粉长度的5～10倍,花粉管在柱头分支中进一步伸长,并开始伸入花柱中生长。(3)授粉后5 h,大量花粉管沿引导组织进入花柱基部与子房顶部之间的子房壁,有少量花粉管在子房壁与外珠被之间的缝隙中生长。(4)授粉后8 h,少量花粉管到达珠孔端。(5)授粉后15～18 h,精核与极核融合,形成初生胚乳核;精、卵核融合,形成合子。(6)授粉后20～30 h,仍可在花柱中见到大量呈束状的花粉管。(7)授粉后48 h,子房内的大部分花粉管出现解体,大多数花粉死亡。研究认为,精细胞到达胚珠的时间为8 h。     

Populationsstatistische Analysen bestätigen die Heterogeneität vonOphrys „arachnitiformis“ (Orchidaceae)

Statistical population analyses have been carried out on so-calledOphrys arachnitiformis, partly sympatricO. sphecodes s. l. as well as on other species ofOphrys (O. holosericea, O. exaltata, O. apulica, O. cornuta, O. biscutella, O. bertolonii, O. bertoloniiformis.). Altogether 63 populations with 521 individuals were studied in regard to 54 morphological parameters. — It can be shown thatO. arachnitiformis is an extremely heterogeneous assemblage which includes taxa of most diverse origin, different degrees of stability and nomenclatorial rank. Only common trait is their very diverse relationships withO. specodes s.l.—The basionymO. arachnitiformis Gren. & Phil. refers to a colour variant ofO. sphecodes Mill. subsp.sphecodes only, and is not applicable to other segments of the assemblage.A late flowering, morphologically and biologically well isolated group of populations from southern France without any perceptible hybrid influence is established as a new species:Ophrys splendida Gölz & Reinhard. Populations from north and central Italy with distinct characters but hybrid influences fromO. holosericea/O. exaltata are calledO. tyrrhena Gölz & Reinhard.O. morisii, an endemic to Sardinia, represents an independent species of still obscure evolution. The hybrid interpretation ofO. catalaunica is statistically corroborated, but somewhat modified. For the remaining segments ofO. arachnitiformis investigated (from Castilia, Dalmatia, and the Monte Gargano) no formal taxonomic proposals are made, but some suggestions about their genesis are possible.

     

Fossil pollen records of the problematical primitive angiosperm familyLactoridaceae in Australia

Microfossils which matchLactoris (Lactoridaceae) pollen more closely than those of any other living angiosperm occur in Campanian to Paleogene sediments around the margins of Australia. These are referred to the fossil genus Lactoripollenites (Zavada & Benson 1987). A species belonging to the same genus occurs in older (Turonian-Santonian) deposits off southern Africa but Australian specimens represent not only the most southern, but also the youngest known (Oligocene) records to date. Our data support suggestions that theLactoridaceae were widespread across the Southern Hemisphere during the Late Cretaceous (Lammers & al. 1986,Zavada & Benson 1987). An homology between gymnosperm sacci and the saccus-like structures found in Lactoripollenites and some specimens ofLactoris pollen is contested, as is the use of (anasulcate) apertures to support the primitive position of the family.     

Pollination ofOpunta basilaris andO. littoralis

The flowers ofOpuntia basilaris andO. littoralis in southern California are visited commonly by beetles(Carpophilus, Trichochrous) and bees (especially anthophorids, megachilids, and halictids), but are pollinated mainly by the bees. This agrees with observations presented in the previous papers in this series for other cactus species in Arizona and Texas. The available evidence indicates that the large, diurnal, cup-shaped flowers in cacti of the American Southwest are primarily bee-pollinated. Our earlier view that theseOpuntia flowers are also pollinated to a significant extent bynitidulid andmelyrid beetles must be modified now in the light of further evidence. Some pollination probably is carried out by small beetles, but it probably represents only a small proportion of the total pollination.Pollination of North American Cacti, III.—See alsoGrant & Grant (1979) andGrant & al. (1979).     

Zur Ultrastruktur und Funktion pollenverbindender Fäden beiEricaceae und anderen Angiospermenfamilien

Viscin threads and other pollen connecting threads of some angiosperm families were investigated, especially those ofEricaceae. According to the definition adopted, viscin threads are ± long exinous processes which consist of exinous material and connect pollen grains or tetrads. Such viscin threads are found within theOnagraceae, Caesalpiniaceae, Ericaceae, andMimosaceae only. While they differ in structure and composition, they always consist of sporopollenin and exhibit a very strong stickiness, even after all viscid substances have been removed by acetolysis. In contrast, the pollen connecting scleroprotein threads ofOrchidaceae and the cellular threads ofStrelitzia reginae Aiton. (Musaceae) are not connected with the exine surface, are destroyed by acetolysis, and thus do not correspond to viscin threads.

     

宁夏枸杞的花粉呈现式样及交配系统研究北大核心CSCD

被子植物的花回馈、雌雄蕊时空分离特征和花粉呈现式样等花部特征及传粉者效率会影响雄性适合度和有性繁殖过程。宁夏枸杞(Lycium barbarum)是中国宁夏、新疆、内蒙等干旱和半干旱地区分布的特有种。该研究对新疆喀什地区宁夏枸杞自然种群的花部综合征、花粉呈现式样、花回馈、传粉者行为与交配方式的关系进行观察及统计分析,以探讨其花粉逐步呈现的适应性及其在提高雌雄繁殖过程中的意义。结果表明:(1)宁夏枸杞的单花寿命为(4.07±0.15) d,而雄性持续时间(0.07±0.01 d)比雌性持续时间短(4±0.01 d);花寿命内雌蕊长度比雄蕊长,属柱头探出式异位类型;花粉呈现式样为不完全逐步呈现。(2)花寿命不同阶段花回馈间存在显著差异。(3)意大利蜜蜂(Apis mellifera)、熊蜂(Bombus sp.)、食蚜蝇(Syrphidae sp.)是宁夏枸杞在自然居群的主要访花者,其中熊蜂和食蚜蝇是主要传粉者,但传粉者效率低,属于高移出低沉积类型。(4)宁夏枸杞的花粉胚珠比(2 448.11±448.32)及授粉实验结果均表现出兼性异交特征;自发自交及人工自花授粉花的座果率及结籽率很低,属于自交不亲和类型;自然传粉花的座果率及结籽率比人工去雄异花低,存在其较高的花粉限制(40.71%)。研究发现,宁夏枸杞花部综合征表现出雌雄异位和花粉不完全逐步呈现式样,这是避免雌雄功能及雄蕊各花药间的干扰、减少花粉同步移出及保障其雄性适合度的有效途径,但自然居群的传粉者种类限制、传粉效率低以及自交不亲性是导致宁夏枸杞花粉限制及降低雌性繁殖成功的主要原因。     

Floral mechanisms in the tribeSalpiglossidae (Solanaceae)

SinceDelpino (1869),Juel (1894, 1911), andMüller (inMöller 1921: 164), the flowers ofSolanaceae have received little attention with regard to function and pollination syndromes. The present paper deals with representatives of 6 of the 9 known salpiglossidean genera. Previous observations are updated and discussed at the tribal level. Most species studied are butterfly- or moth-pollinated. With the exception ofSalpiglossis, the fertile floral parts are concealed in the corolla tube, and their arrangement is specially suited for deposit of the pollen on the lepidopteran tongue. Particularly notable are (a) abundant stigmatic secretion that makes the pollen sticky, and (b) versatile anthers that optimize contact between the tongue and the thecae.Brunfelsia andBrowallia exhibit a mechanism analogous to that ofApocynaceae, however, with two entrances instead of five. When the tongue is inserted, it is forced to contact the stigma and becomes glued with its secretion. When the tongue is pulled out, it touches the anthers and causes slight balancing movement. InStreptosolen, very probably an ornithophilous descendant of theBrowallia stock, the mechanism is much simplified.Leptoglossis andHunzikeria bear a novel device for pollen deposition: there are two fertile wheel-like anthers that are capable of full rotation up to eight turns.     

野慈姑(Sagittaria trifolia)人工授粉的有效性:授粉工具与花粉保存

人工授粉作为一项关键性技术在生态研究与农业生产领域广泛应用,但是授粉过程中的工具有效性以及花粉保存尚未受到研究者的关注。以植物野慈姑为试验材料,研究了人工授粉方式和花粉保存条件对繁殖的影响。两年的结果表明,相较于直接接触式授粉,借助毛刷工具授粉显著降低了野慈姑的座果概率和种子数。花粉经过半小时野外高温保存后,其授粉的座果概率显著高于对照组,但单果种子数和种子大小保持稳定。综上,在野慈姑的人工授粉中应避免使用毛刷等工具,离体花粉可置于野外环境适当保存。在相关应用中,研究人员应当警惕工具授粉造成的负面影响,注意比较工具与其他授粉方式的等效性,保证实验的科学性。