FLORA OF THE BRANDON LIGNITE. IV. ILLICIACEAE

Illicium avitum is described from the Early Oligocene Brandon Lignite of Vermont. The remains consist of immature fruiting axes, preserved shortly after fertilization. The short pedicel terminates in a torus bearing 13 conduplicate carpels in a single whorl. These are surrounded by two whorls of approximately 20 to 30 staminal scars each, which are in turn surrounded by 24–40 perianth scars. The immature seeds within the carpels possess developing embryos and seed coats. Although comparisons with certain modern species are possible, the available characters are not sufficient to permit its association with any one modern species or group of species. The fossil material provides limited evidence for a reduction in the numbers of floral parts through time in Illicium.     

STOMATA ON THE FRUITS AND SEEDS OF ESCHSCHOLZIA (PAPAVERACEAE)

Stomata are present on the outer and inner fruit walls and seed coats of Eschscholzia californica, E. covillei, E. glyptosperma, E. lemmonii and E. minutiflora. The stomata on the inner fruit wall and seed coat remain constantly open, even under plasmolyzing conditions, whereas those of the outer fruit wall are able to open and close. This allows for gas exchange in these chlorophyllous structures. Fibrous bundle caps in the costal regions of the fruit act as windows allowing light transmission to the photosynthetic seeds within. Preliminary results show that the total photosynthesis by the fruits and seeds of Eschscholzia californica together appears to at least balance respiratory losses, and under favorable conditions might significantly contribute to seed and fruit development.     

FRUITS AND SEEDS OF TRIBE GORDONIEAE (THEACEAE) FROM THE EOCENE OF NORTH AMERICA

A new genus and species Gordoniopsis polysperma and two new species of Gordonia (Gordonieae, Camellioideae, Theaceae) are described based on fossil fruit and seed remains. These specimens are part of a large flora consisting of various plant organs from the middle Eocene Claiborne Formation in western Kentucky and Tennessee. Gordoniopsis is a five-valved loculicidally dehiscent capsule similar to capsules of Gordonia but differing in having unwinged seeds and a greater number of seeds per locule. The two Gordonia species are among the earliest unequivocal records of the genus and two of only four fossil Gordonia species known with in situ seeds. Two extinct genera, Gordoniopsis and Andrewsiocarpon, and the extant genus Gordonia in the tribe Gordonieae are known from the middle Eocene Claiborne flora, suggesting an early radiation within the tribe. Based on a survey of Recent fruits and seeds we concur with Keng's proposal to merge Laplacea with Gordonia.     

被子植物果实和种子化石的获取和研究：介绍B.H.Tiffney的原理和方法

近年来繁殖器官化石的研究已成为国际被子植物化石研究领域的热门之一,其研究方法和技术经过多年的探索也已日趋成熟,美国古植物学家ＢｒｕｃｅＨ．Ｔｉｆｆｎｅｙ根据自己多年的研究积累并吸收同行的经验对获取和研究分散保存在岩石中的被子植物果实和种子化石的原理和方法进行了系统的总结和介绍（Ｔｉｆｆｎｅｙ,１９９）为方便国内同行门熟悉和运用这些方法对我国可能产出的繁殖器官化石进行研究,本文特将该文中涉及实验原理     

STOMATA ON SEEDS AND FRUITS OF BAUHINIA (LEGUMINOSAE: CAESALPINIOIDEAE)

Seeds of 45 species of Bauhinia (Leguminosae: Caesalpinioideae) were studied by scanning electron microscopy. Seeds of eight species have stomata which are mostly normal in appearance but lack subsidiary cells and are slightly recessed. Varying degrees of distortion or obscuring cuticular deposits were found in some species. This is the first unambiguous report of stomata on seeds of Leguminosae. Fruits of two of the eight species were also examined. Raised stomata with conspicuous subsidiary cells were found only on the outer pericarp surface.     

PERMINERALIZED FRUITS AND SEEDS FROM THE PRINCETON CHERT (MIDDLE EOCENE) OF BRITISH COLUMBIA: ARACEAE

Some of the most conspicuous fruit and seed remains from the Middle Eocene Princeton chert locality (Allenby Formation) are assignable to the Araceae. Several thousand campylotropous, reniform, spiny seeds 2.5–3.2 mm long x 1.8–2.3 mm wide have been found dispersed in the chert. Two fruits, each with a single locule and at least eight ovules, show three distinct wall layers and appear to have been fleshy. The two layers of seed integument have pitted isodiametric sclereids aligned in radial rows, the outermost being thinner walled. Spines are borne in three rows on the dorsal seed surface while the ventral side is flattened. Idioblasts that probably contained raphides are present in the outer integument. Nucellar tissue is attached to the integument for most of its length and is well-preserved in some seeds near the chalaza and in the large conical shaped area beneath the micropyle. Endosperm cells with dark contents and curved, linear, monocotyledonous embryos are present in some seeds. Sections of seeds of living araceous taxa of the subfamilies Monsteroideae (Epipremnum, Rhodospatha) and Lasioideae (Urospatha, Cyrtosperma) were made for comparison. The fossil seeds represent a new taxon most closely related to Cyrtosperma, Keratosperma allenbyensis Cevallos-Ferriz et Stockey gen. et sp. nov., Family: Araceae, Subfamily: Lasioideae, Tribe: Lasieae. The Princeton remains are the oldest described seeds of this tribe known to date and add to our knowledge of the subtropical elements of the Princeton flora.     

二十三种药用种子(或果实)中油的化学组成

本文报道了二十三种药用种子(或果实)的含油率和油的化学组成成分,它们分属于二十个科二十二个属中。本文所发表的大部分资料尚未见国内外文献的报道。     

AUTOROTATION, SELF-STABILITY, AND STRUCTURE OF SINGLE-WINGED FRUITS AND SEEDS (SAMARAS) WITH COMPARATIVE REMARKS ON ANIMAL FLIGHT

• 1 A samara is a winged fruit or seed that autorotates when falling, thereby reducing the sinking speed of the diaspore and increasing the distance it may be transported by winds. Samaras have evolved independently in a large number of plants.
• 2 Aerodynamical, mechanical, and structural properties crucial for the inherent self-stability are analysed, and formulae for calculation of performance data are given.
• 3 The momentum theorem is applied to samaras to calculate induced air velocities. As a basis for blade element analysis, and for directional stability analysis, various velocity components are put together into resultant relative air velocities normal to the blade's span axis for a samara in vertical autorotation and also in autorotation with side-slip.
• 4 When falling, a samara is free to move in any sense, but in autorotation it possesses static and dynamic stability. Mainly qualitative aspects on static stability are pre sented. Simple experiments on flat plates at Reynolds numbers about 2000 as in samaras, showed that pitch stability prevails when the C. M. (centre of mass) is located 27–35 % of the chord behind the leading edge. The aerodynamic c.p. (centre of pressure) moves forward upon a decrease of the angle of attack, backward upon an increase. In samara blades the c.m. lies ca. one-third chord behind the leading edge, and hence the aerodynamic and centrifugal forces interact so as to give pitch stability, involving stability of the angles of attack and gliding angles.
• 5 Photographs show that the centre of rotation of the samara approximately coincides with its c.m.
• 6 The coning angle (blade angle to tip path plane) taken up by the samara is determined by opposing moments set up by the centrifugal and aerodynamic forces. It is essentially the centrifugal moment (being a tangent function of the coning angle, which is small) that changes upon a change of coning angle, until the centrifugal and aerodynamic moments cancel out at the equilibrium coning angle.
• 7 Directional stability is maintained by keeping the tip path plane horizontal whereby a vertical descent path relative to the ambient air is maintained. Tilting of the tip path plane results in side-slip. Side-slip leads to an increased relative air speed at the blade when advancing, a reduced speed when retreating. The correspondingly fluctuating aerodynamic force and the gyroscopic action of the samara lead to restoring moments that bring the tip path plane back to the horizontal.
• 8 Entrance into autorotation is due to interaction between aerodynamic forces, the force of gravity, and inertial forces (when the blade accelerates towards a trailing position behind the c.m. of the samara).
• 9 The mass distribution must be such that the c.m. lies 0–30 % of the span from one end. In Acer and Plcea samaras the C.M. lies 10–20% from one end, thereby making the disk area swept by the blade large and the sinking speed low.
• 10 The blade plan-form is discussed in relation to aerodynamics. The width is largest far out on the blade where the relative air velocities are large. The large width of the blade contributes to a high Re number and thus probably to a better L/D (lift/drag) ratio and a slower descent.
• 11 The concentration of vascular bundles at the leading edge of the blade and the tapering of the blade thickness towards the trailing edge are essential for a proper chord wise mass distribution.
• 12 Data are given for samaras of Acer and Plcea, and calculations of performance are made by means of the formulae given in the paper. Some figures for an Acer samara are: sinking speed 0.9 m/sec, tip path inclination 15°, average total force coefficient 1.7 (which is discussed), and a L/D ratio of the blade approximately 3.
• 13 The performances of samaras are compared with those of insects, birds, bats, a flat plate, and a parachute. They show the samara to be a relatively very efficient structure in braking the sinking speed of the diaspore.
• 14 In samaras the mass, aerodynamic, and torsion axes coincide, whereas in insect wings the torsicn axis often lies ahead of the other two. Location of the torsion axis in front of the aerodynamic axis in insects tends towards passive wing twisting and passive adjustment of the angles of attack relative to the incident air stream, the direction of which varies along the wing because of wing flapping.
• 15 Location of the mass axis behind the torsion axis may lead to unfavourable

     

木通科、大血藤科花粉壁的超微结构研究

应用透射电子显微镜(TEM)观察了木通科Decaisnea,Sinofr-anchetia,Holboellia,Stauntonia属以及大血藤科Sargentodoxa属共18种植物花粉壁的超微结构。所观察的木通科和大血藤科植物具较发达的覆盖层和柱状层;外壁内层以及内壁均在萌发沟处明显增厚;基层通常不甚发达。与扫描特征相对应的覆盖层结构特征,显示出类群的特异性。在Stauntonia属,覆盖层富于形态变化,反映出该属在木通科中较进化的地位;大血藤(Sarg-entodoxa cuneata)花粉壁结构隶属木通型花粉结构,表明大血藤科与木通科的密切关系。     

POLLEN MORPHOLOGY AND THE RELATIONSHIPS OF CIRCAEASTER,OF KINGDONIA,AND OF SARGENTODOXA TO THE RANUNCULALES

The pollen of three monotypic genera, Circaeaster, Kingdonia, and Sargentodoxa has been examined by light and scanning electron microscopy and in the case of the last genus, also by transmission electron microscopy. The type of tectum found in Circaeaster and Kingdonia, derivations of a compound layer of striae, has a restricted distribution in the Order Ranunculales. Of 64 genera examined in this order only six had species with a similar tectum. They include Achlys, Epimedium, Jeffersonia, and Vancouveria of the Berberidaceae s.l., the controversial Hydrastis, and Trollius of the Ranunculaceae. Circaeaster and Kingdonia have been considered as related since both have rare and primitive vegetative characteristics, the most notable being open dichotomous leaf venation. They are probably best treated as a ditypic family, Circaeasteraceae. The pollen of Sargentodoxa, especially the structure of the exine, closely resembles that of the Lardizabalaceae. However, the fruits of Sargentodoxa have been considered to be distinct from those of the Lardizabalaceae, suggesting that it be treated as a separate, but closely allied, family.     

姜属植物种子的解剖学和组织化学研究

本文报道以斑蝉姜、珊瑚姜和多穗姜为材料的姜属种子解剖学和组织化学研究结果。结果表明,姜属种子较大,基部具一膨大的种阜状结构,膜质假种皮２－５裂,裂片指状或瓣状。种皮黑褐色,一般平滑,由外种皮、中种皮与内种皮组成。外种皮为一层表皮细胞。中种皮由各含一层细胞的下皮层和半透明细胞层与含（２）３－４层薄壁细胞的色素层组成。半透明细胞体积很大,细胞内的不定形块状物含有脂类;色素层细胞体积小,不含或仅含少许色     

大血藤科花粉形态及外壁超微结构的研究

对大血藤科及木通科的八月瓜属ＨｏｌｂｏｅｌｌｉａＷａｌｌ．和木通属ＡｋｅｂｉａＤｅｃｎｅ花粉进行了光镜及电子显微镜的观察研究。研究结果表明,其花粉形态具有较为明显的相似性,如花粉均为３沟,外壁表面具穴状纹饰,甚至大小也很近似。但从其外壁结构看,大血藤花粉的外壁内层为结均一的致密层组成     

广西宁明第三纪类黄杞翅果化石

广西宁明西南约4km处新发现的一个植物群中,含有一些与胡桃科黄杞属现生种的翅果在形态上近似的化石。它们的果翅三裂,裂片具有羽状脉序。这些化石的一部分特征与黄杞属的裸果黄杞组的相似,另一部分特征与该属的黄杞组的相似,因而难以将它们归于其中的任何一组,作者将其归于类黄杞属。后者是胡桃科黄杞族的一个器官属,与目前分布于我国长江以南及东南亚地区的黄杞属以及分布于美洲新大陆的美黄杞属有密切亲缘关系。在地史时期,类黄杞属的代表较广泛地分布于北半球。然而,当前化石却是这类化石在我国南方首次被发现,这为探讨黄杞族的演化提供了重要线索。从当前化石的研究和有关文献中得知,黄杞族祖先的翅果形态与裸果黄杞组的现生种可能有某种程度的近似。