Dichilanthe, an unusual Asiatic Rubiaceae with "Lonicera flowers" and "dipterocarp fruits"

Dichilanthe, a disjunctly distributed, arborescent Southeast Asiatic genus (D. zeylanica: Sri Lanka; D. borneensis: West Borneo) with collar-like, persistent stipules, has strongly zygomorphic, ornithophilous flowers which show secondary pollen presentation. The curved corolla is two-lipped. The upper lip consists of 2, and the lower lip of 3 fused corolla lobes. The calyx, too, is zygomorphic. The curved, exserted style ends in a swollen “stylar head' which apically bears two small stigmatic (receptive) areas in a zygomorphic arrangement. The flowers are borne in compact, terminal heads, held together by enlarged stipules of a bract-pair immediately below the inflorescence. The dispersal units (diaspores) mimic dipterocarp fruits. They consist of a persistent, wing-like pair of bracts whose±cuplike stipules enclose the fruits. The diaspores break off at the node immediately below the bract-pair, where there is a distinct abscission zone. Initial on”primary“dispersal by wind may be followed by facultative”secondary“dispersal by floating in water.”Pith tissue“produced by each fruit of the diaspore, and the air spaces contained therein, are likely to be adaptations to floating. This”pith tissue“, a loose, parenchymatic,± irregularly arranged area of the fruit wall which partially disintegrates during fruit maturation, represents a modified portion of the endocarp; the remainder of the endocarp is”normal“sclerenchymatic tissue coating the two locules. The initial stages of this endocarp differentiation are already observable in early developmental stages, i.e., in ovaries of flower buds and open flowers. The bicarpellate ovaries contain a solitary, anatropous pendulous ovule per locule. Viable seeds have large embryos and only c. 5–6 layers of oily endosperm; their exotesta cells have delicate, ring-like thickenings. In developing fruits of individual inflorescences, a high frequency of seed abortion was noted. Not uncommonly, there is only a single viable seed per dispersal unit, i.e., only a solitary seedling emerging from a diaspore. Germination of the seeds is cryptocotylar. The pollen of D. zeylanica is suboblate and 5- or 6-colpate (with the colpi being rather short); the exine is finely reticulate. In spite of several of its character states being unusual and aberrant, the tribal position of Dichilanthe in the Guettardeae is not questioned, although it is concluded that the genus occupies a rather isolated position in the tribe.     

Canrightiopsis,a new Early Cretaceous fossil with Clavatipollenites-type pollen bridge the gap between extinct Canrightia and extant Chloranthaceae

Canrightiopsis with three species (C. intermedia, C. crassitesta, C. dinisii) is described from the Early Cretaceous of Portugal based on small, one-seeded berries. The fruits are derived from bisexual flowers with three stamens borne on one side of the ovary. There are no traces of a perianth. Pollen is of the Clavatipollenites-type, monocolpate, semitectate, reticulate-columellate with heterobrochate reticulum and muri with beaded supratectal ornamentation. The ovary is unilocular with a single pendant, orthotropous and bitegmic ovule. The seed is endotestal. The endotesta consists of one layer of palisade-shaped crystal cells with fibrous infillings. The fruit wall has resin bodies or cavities from presumed ethereal oil cells sometimes seen as stomata-like structures on the fruit surface. A phylogenetic analysis resolves Canrightiopsis as a close relative of extant Chloranthaceae, particularly close to extant Chloranthus and Sarcandra. All three taxa share the one-sided position of the stamens on the ovary. An evolutionary sequence from fossil Canrightia to fossil Canrightiopsis and extant Chloranthus and Sarcandra is suggested by loss of perianth, reduction in number of ovules and stamens and displacement of stamens to one side of the ovary. Canrightiopsis also shares several critical features with extant Ascarina including monoaperturate pollen and beaded supratectal ornamentation of the pollen wall.     

Structure and development of the ovule and seed in Aristolochiaceae, with particular reference to Saruma

All members of Aristolochiaceae have anatropous, bitegmic, crassinucellate ovules, which are endostomic except in Saruma and Asarum arifolium where ovules are amphistomic. The outer integument is two cell-layered and the inner integument is three cell-layered. The chalazal megaspore is the functional one. All these conditions appear to be plesiomorphic for the order Piperales, which consists of five families, Aristolochiaceae, Hydnoraceae, Lactoridaceae, Piperaceae and Saururaceae. The embryo sac in Aristolochiaceae is eight-nucleate and corresponds to the Polygonum type; a hypostase is frequently present in this family. The seed coat of Aristolochia s.l., Asarum, Saruma and some Thottea species consists primarily of a two cell-layered testa, and a three cell-layered tegmen. In some species the cells of the outer epidermis become radially elongated, forming reticulate wall thickenings. Cells of the inner layer of the testa have crystals and thickened inner walls. The three layers of the tegmen are tangentially elongated, and become cross fibres at maturity, as fibres of the outer and inner layers are parallel to the seed axis, whereas those of the middle layer are perpendicular to it. This type of seed coat anatomy is synapomorphic for Aristolochiaceae. In addition, the gross morphology of the seed and elaiosome histology are remarkably similar in Asarum and Saruma, thus supporting a sister-group relationship between them. Embryological and seed characters do not supply any synapomorphy that support a close relationship between Aristolochiaceae, Hydnoraceae and Lactoridaceae. Instead, some seed features such as the absence of seed appendages and the collapsed cells of endotesta may indicate a close relationship of Lactoris with Piperaceae plus Saururaceae, although this is the subject of further analysis.     

Embryology and systematic position ofLiparis (Orchidaceae)

The embryology ofLiparis paradoxa andL. rostrata has been studied. The young anther wall consists of an epidermis, endothecium, three middle layers and secretory tapetum with uninucleate cells. In the mature anther, two or three sub-epidermal layers develop fibrous thickenings. The anther wall development corresponds to the massive type. Simultaneous cytokinesis results in decussate, isobilateral, linear, T-shaped and tetrahedral pollen tetrads. The pollinia are compact and at anthesis the pollen grains are 2-celled. Ovules are anatropous, bitegmic and tenuinucellate. Both the integuments are dermal in origin and 2-layered. Development of female gametophyte is of the monosporic, 8-nucleate type. Double fertilization occurs. The primary endosperm nucleus degenerates. The mature embryo is organized from the derivatives of tiers 1, 1, m, and n. Its development conforms to a variation of the Onagrad type. The seed coat is formed entirely by the outer layer of the outer integument. There are three sterile and three fertile valves in the ovary. In the prefertilization stages valves consist of parenchymatous cells. After fertilization, the sterile valves become sclerenchymatous whereas the fertile valves remain parenchymatous. The embryological characters support the disputed systematic position ofLiparis within subtribeLiparidinae ofEpidendreae.     

EMBRYOLOGICAL DEVELOPMENT OF LACHNANTHES CAROLINIANA (HAEMODORACEAE)

Embryological development of Lachnanthes caroliniana was studied utilizing standard anatomical techniques and SEM. Lachnanthes has a monocotyledonous anther wall development (endothecial cells with spiral secondary wall thickenings), successive microsporogenesis, and amoeboid (periplasmodial) tapetal development. Mature pollen grains are 2-nucleate with a proximal, fusiform generative cell. Ovules are initiated as 5–7 cylindrical primordia from a common placental base. Basal ovular swellings collectively contribute to the enlarged, peltate placenta. Mature ovules are pleurotropous, anatropous, bitegmic, and crassinucellate; the nucellus consists of a chalazal hypostase, radially elongate lateral cells, and a prominent micropylar nucellar cap. Megasporogenesis is successive, forming a linear tetrad of megaspores. Megagametogenesis is monosporic; the female gametophyte is of the Polygonum-type with relatively large, pyriform antipodals. Endosperm formation is helobial, resulting in the establishment of a ring of four thick-walled basal endosperm cells (the chalazal chamber) and numerous free nuclei (in the micropylar chamber). The mature cellular endosperm is filled with starch grains and has a chalazal cavity and a thick-walled peripheral layer. The discoid, peltately attached seeds have marginal wings derived by anticlinal divisions and buckling of the outer integument alone. Inner and middle cuticular layers are present in the seed coat. Lachnanthes is similar to all other investigated members of the Haemodoraceae in major embryological features. The significance of embryological evidence with regard to interfamilial classification is discussed. Future studies of ovule and seed development may prove valuable in phylogenetic studies in assessing the homology of placental, ovule, and seed morphology and anatomy.     

HALLETHECA RETICULATUS GEN. ET SP. N.: A SYNANGIATE PENNSYLVANIAN PTERIDOSPERM POLLEN ORGAN

A new structurally preserved synangiate pollen organ is described from the upper Pennsylvanian (Mattoon Formation) of southeastern Illinois. The specimen of Halletheca reticulatus gen. et sp. nov. measures approximately 1.5 cm long by approximately 5.0 mm in diam, and consists of five elongate sporangial tubes equidistantly arranged around a solid central column, and embedded in a thin-walled ground tissue. The vascular system consists of five terete bundles characterized by scalariform tracheids. Sporangia are thick-walled and contain pollen of the Monoletes-type. Ultrastructural studies of the pollen grain wall show it to consist of a uniform network of muri which branch and re-unite to form small lumina. A comparison of the ultrastructure of the pollen grain wall of the new fructification is made with the wall organization found in similar pollen of Dolerotheca. Relationships between the new taxon and other presumed seed fern pollen organs differing in preservation mode are discussed.     

DISPERSAL ECOLOGY OF VANCOUVERIA (BERBERIDACEAE)

All Vancouveria species are habitual myrmecochores of the Viola odorata type. The anatropous, bitegmic seed develops an unusual elaiosome in the form of a large, empty, folded and lobed sac of epidermal tissue. The thin-walled assimilating capsule dehisces along an oblique weak zone that probably represents the suture between two fused and unequal carpels. In V. hexandra the capsule opens early to expose immature assimilating seeds. Decurved pedicels, down-turned fruits, and weak funiculi produce tachyspory. The related Epimedium, Jeffersonia, and Plagiorhegma have appendaged seeds and other possible myrmecochorous features resembling those of Vancouveria. Myrmecochory was probably established in the early or middle Tertiary period. The Vancouveria-Epimedium complex indicates that enormous plant migrations may be accomplished by means of ants.     

Studies in the embryology of compositae

The male and female gametophytes formation, fertilisation, and embryo development were observed inSolidago canadensis andConyza stricta. The anther is tetrasporangiate and its wall development conforms to the Dicotyledonous type. Simultaneous cytokinesis in pollen mother cells results in tetrahedral or isobilateral tetrads. Pollen polymorphism is a common feature inS. canadensis. The ovule is anatropous, unitegmic and tenuinucellate showing an ovular vascular strand. The female archesporium is hypodermal and single celled. The development of the embryo sac is of the Polygonum type. InS. canadensis seed set is completely absent and multiplication occurs by vegetative propagation. InC. stricta fertilisation is progamous. Triple fusion and syngamy occur more or less simultaneously. Endosperm is cellular and the embryogeny corresponds to the Asterad type. A part of the thesis accepted for the Ph. D. degree of the Andhra University.     

Campynemanthe (Campynemaceae): Morphology, microsporogenesis, early ovule ontogeny and relationships

Campynemanthe Baill. consists of three species endemic to New Caledonia. Two species are studied and compared. The tapetum is secretory with 2-nucleate tapetal cells. Microsprogenesis is successive, microspore tetrads are isobilateral and the pollen grains are free and inaperturate or have a weakly defined aperture. Placentation is axile with 3–4 ovules in each of the three locules. Ovules are anatropous and crassinucellate with the micropyle formed by the inner integument alone. The archesporial cell cuts off a parietal cell, which divides to form a parietal tissue. The nucellar epidermis divides periclinally at the nucellar apex to become 2-layered. The megaspore tetrad is T-shaped, in which the micropylar megaspore cells are separated by an oblique wall. The chalazal megaspore enlarges and apparently developes into a Polygonum-type embryo sac, but a mature embryo sac has not been seen. The ripe seeds are pale and non-phytomelaniferous. They have copious endosperm rich in fatty oils. The embryo is minute. These characters and gross morphological similarities support relationship with Campynema Labill., but there are also conspicuous differences. The two genera are considered related. They also closely approach genera of the variable family Melanthiaceae and there are reasons to include them in this family.     

Seed germination patterns of Salvia mellifera in fire-prone environments

Summary I examined the effects of pollen loads containing pollen from one, three and five donors on fruit production and fruit quality in Campsis radicans. Number of pollen donors had no significant effect on % fruit production, seed number, seed weight or seed germination. In singledonor pollinations the identity of the donor did have a strong effect on the above parameters. Furthermore, the best single donor sired fruits with more seeds and heavier seeds than any mixture containing this donor. This pattern indicates interference of pollens or preemption of some ovules by the inferior pollen. In Campsis, therefore, the number of pollen donors contributing to a pollen load is less important than the identity of these donors in determining fruit production and fruit quality. Seeds from fruits resulting from mixed pollination were slightly more variable than seeds from fruits resulting from single-donor pollinations.     

小叶丁香引种栽培条件下种子败育的解剖学研究

为探讨小叶丁香在北京栽培条件下种子败育的问题,对其胚胎发育过程进行了解剖学观察研究。结果显示:(1)小叶丁香人工异花授粉坐果率为20.37%,天然授粉坐果率为9.13%,人工自花授粉以及去雄套袋授粉均未坐果;各种授粉方式结实率均为0。(2)小叶丁香花药壁发育为基本型,腺质绒毡层,胞质分裂为同时型,小孢子四分体排列方式以四面体型为主,2-胞成熟花粉;倒生胚珠,单珠被,薄珠心,直线型大孢子四分体,胚囊发育为蓼型,核型胚乳,胚发育为紫菀型,先后形成球形胚、心形胚、鱼雷形胚和子叶胚;9月1日以后,子叶胚发育停滞,细胞逐渐降解。研究表明,栽培条件下,小叶丁香为异花授粉植物,人工异花授粉可提高植株坐果率,但未获得种子;其大小孢子及雌雄配子体发育、传粉受精过程、胚胎发育初期均正常,但后期发育停止,是小叶丁香引种栽培条件下种子败育的关键环节。     

凤仙花花药发育中多糖和脂滴组织化学研究

以不同发育时期的凤仙花花药为实验材料,采用组织化学方法,对花药发育中的结构变化及多糖和脂滴物质分布进行观察。结果表明:(1)凤仙花的花药壁由6层细胞组成,包括1层表皮细胞,2层药室内壁细胞,2层中层细胞和1层绒毡层细胞。其中绒毡层细胞的形态不明显,很难与造孢细胞区分,且在小孢子母细胞时期退化。(2)在小孢子母细胞中出现了一些淀粉粒,但减数分裂后,早期小孢子中的淀粉粒消失,又出现了一些小的脂滴;随着花粉的发育,小孢子形成大液泡,晚期小孢子中的脂滴也消失;小孢子分裂形成二胞花粉后,营养细胞中的大液泡降解、消失,二胞花粉中又开始积累淀粉;接近开花时,成熟花粉中充满细胞质,其中包含了较多的淀粉粒和脂滴。(3)在凤仙花的花药发育中,绒毡层细胞很早退化,为小孢子母细胞和四分体小孢子提供了营养物质;其后的中层细胞退化则为后期花粉发育提供了营养物质。     

The corystosperm pollen organ Pteruchus from the Triassic of antarctica

The permineralized corystosperm pollen organ Pteruchus is described from the early Middle Triassic of Antarctica. Pteruchus fremouwensis consists of an axis bearing numerous, helically arranged microsporophylls, each of which terminates in a distal flattened head. The axis is 1–2 mm in diameter and eustelic. Spherical to elliptical secretory cavities are present in the ground tissue of the axis, microsporophyll, and pollen sac wall. The basal stalk of the microsporophyll is vascularized by a C-shaped strand that gives rise to a midvein and numerous lateral veins in the distal head. At least 38 pollen sacs are borne on the abaxial surface of the microsporophyll head. These are arranged in pairs on either side of lateral veins. Each pollen sac is sessile, elongated, and uniloculate. The pollen sac wall is several cell layers thick early in ontogeny, but reduced to a single layer in thickness when mature. Dehiscence is longitudinal along the inner surface. Pollen is monosulcate and bisaccate, and of the Alisporites-type. The Triassic specimens are the first structurally preserved pollen organs of the Pteruchus-type and can be related to the associated corystosperm stem and leaf genera based on the presence of unique secretory cavities. The morphology of Pteruchus and the relationship of this pollen organ with other Mesozoic and Paleozoic pollen organs is discussed.     

Studies in the embryology of the diandrous orchidCypripedium cordigerum (Cypripedieae,Orchidaceae)

The anther wall layers ofCypripedium cordigerum are six to eight. The glandular tapetum is 2- or 3-layered and its cells are uninucleate. Simultaneous cytokinesis results in decussate, isobilateral and tetrahedral pollen tetrads. Ripe pollen grains are 2-celled. The mature ovules are anatropous, bitegmic and tenuinucellate. Both the integuments are dermal in origin and 2-layered. The inner integument alone forms the micropyle. The female gametophyte is 6-nucleate and bisporic. The reduction of nuclei is due to the strike phenomenon. Double fertilization occurs. The primary endosperm nucleus divides to form two free endosperm nuclei. The mature embryo is undifferentiated. The cells ca, m and n contribute to the embryo. The suspensor is single-celled. The seed coat is formed entirely by the outer layer of the outer integument. There are three sterile and three fertile valves in the ovary. In the prefertilization stages these valves consist of parenchymatous cells with starch and raphides. After fertilization, the sterile valves develop sclerotic cells whereas the fertile valves remain parenchymatous. The pericarp structure and embryological features support the retention of tribeCypripedieae within theOrchidaceae.     

Preliminary palaeobotanical notes on the Early Cretaceous Cintura Formation (Sonora,Mexico)

The Cintura Formation of Albian–Cenomanian age in the Cabullona Basin yielded an important fossil flora, including palynomorphs, leaf impressions and fossil trunks. At the base of the Marquechi Member a poorly preserved palynomorph assemblage is recognised. The palynological assemblage is dominated by gymnosperms, mainly by cheirolepidiacean genus Classopollis. A noteworthy feature is the presence of angiosperm pollen grains of the genera Clavatipollenites, Retimonocolpites and Tucanopollis. A rich, diverse and well-preserved macroflora of leaf impressions has been observed in the uppermost part of this formation belonging to the San Juan Member. There are at least eight morphospecies of leaves including an abundance of taxa with possible botanical affinities to the family Sapindaceae. The angiosperm pollen grains together with the sapindalean leaves constitute the oldest record of such remains in Mexico.     

Reproductive ecology of Thymelaea velutina (Thymelaeaceae)- Factors contributing to the maintenance of heterocarpy

Thymelaea velutina (Thymelaeaceae) is a dioecious shrub that presents a unique type of heterocarpy which consists of the simultaneous production of dry and fleshy fruits. It is endemic to the Balearic Islands (Western Mediterranean) and is found both in dunes and mountain areas. The goal of this study was to identify which factors influence the production of both fruit types, examining the variation of their effects at a spatio-temporal scale (comparing two localities in different years). Specifically, we investigated (1) whether pollen limitation influences the type of fruit produced, and (2) the possible differences in seed size, mass, dispersal capacity, seed predation, germination patterns and seedling survival between fruit types. We also examined if the production of fleshy fruits was modified with the application of gibberellins to reproductive branches. Although fleshy fruits were consistently more abundant than dry ones at both populations, their proportion was significantly higher at the site with greater precipitation. The addition of either pollen or gibberellins did not affect the proportion of each fruit type. Seeds in fleshy fruits are consistently larger, heavier and more likely to be dispersed than seeds in dry fruits, but germinability, germination rate and seedling survival was similar among fruit types. Heterocarpy in this species is currently maintained as there is no apparent factor that exerts any strong selective pressure on either fruit type. The two fruit types might even have different `functions', one serving especially for dispersal and population expansion and the other for producing a seed bank that ensures an eventual germination.     

Early history of theJuglandaceae

The major radiation of theJuglandaceae occurred during the early Tertiary as recorded by the proliferation of juglandaceous pollen and the appearance of fruits representing extinct and extant genera of the family. Juglandaceous pollen types of the Paleocene were predominantly triporate and exhibited a greater diversity in patterns of exinous thinning than occurs in the family today. Analyses of in situ pollen from early Tertiary juglandaceous inflorescences confirms the taxonomic value of certain patterns of exinous thinning. Data from co-occurring fruits and pollen indicate that relatively unspecialized, isopolar triporate pollen of the type presently confined to the tribeEngelhardieae also occurred in other tribes of the family during the Paleocene. Pollination has been mostly anemophilous throughout the Tertiary. Both wind and animal fruit-dispersal syndromes were established early in the radiation of the family but a greater diversity of wind-dispersed genera has prevailed.     

Embryology of the dioecious Woonyoungia septentrionalis (Magnoliaceae)

The embryological characteristics and ovular integument development of the dioecious species Woonyoungia septentrionalis (Dandy) Law (Magnoliaceae), which are poorly understood, were investigated under laser scanning confocal microscope (LSCM) and light microscope (LM). The embryological characteristics conform to most of the previously studied species in Magnoliaceae. The anther has 4 microsporangia, and the anther wall develops according to the dicotyledonous type. Cytokinesis at meiosis of the microspore mother cells follows a modified simultaneous type, giving rise to isobilateral or decussate tetrads, and a cell plate is absent, but a membrane was observed. Mature pollen grains are 2‐cellular and have high germination rates. The ovule is anatropous, crassinucellate and bitegmic, and meiotic result in linear tetrads of megaspores, the one at the chalazal end functions directly as an embryo‐sac cell. The development of the embryo sac is of the Polygonum‐type and endosperm formation is of the nuclear type. The outer integument of the ovule differentiates into an outer fleshy and an inner stony layer while the inner integument is reduced to a tanniniferous layer. The normal embryological development, high germination rates of pollen and high seed set indicate that the primary reason for the decline of the species is not to be found in these developmental processes.     

鹅毛竹大小孢子及雌雄配子体发育

利用扫描电镜、透射电镜、石蜡切片,对鹅毛竹的花芽分化、大、小孢子及雌、雄配子体的发育进行了详细观察.结果发现:鹅毛竹花药具4个药室,花药壁由表皮、药室内壁、中层、绒毡层4层结构组成,花药壁发育为单子叶型,绒毡层为腺质型,小孢子母细胞减数分裂中的胞质分裂为连续型,产生左右对称型小孢子.鹅毛竹成熟花粉大多2细胞型,都具1个萌发孔.鹅毛竹子房为单子房,子房1室,侧膜胎座,一个倒生胚珠,双珠被,薄珠心.大孢子母细胞由一个雌性孢原细胞直接发育而成,大孢子四分体呈线型,合点端一个大孢子分化为功能大孢子,由功能大孢子经过3次有丝分裂形成8核胚囊,发育类型为蓼型,位于核点端的3个细胞核进行多次分裂形成多个反足细胞.至此,成熟胚囊形成.并就鹅毛竹不结实的原因进行了探讨.