THE DEVELOPMENTAL ANATOMY OF OPUNTIA BASILARIS. I. EMBRYO,ROOT, AND TRANSITION ZONE

The large seeds of Opuntia basilaris Engelm. & Bigel. show an unusually high percentage of germination, followed by a rapid development of the seedling during the first 30 days of growth. The primary root has six xylem arms alternating with six phloem poles around a large central pith. Development of metaxylem opposite each of the primary phloem poles results in the formation of eight collateral bundles. Secondary and tertiary roots have four xylem and phloem poles with xylem developing to the center of the stele. The transition zone is characterized by a gradual disappearance of all but two of the primary xylem arms of the root. Metaxylem development in the central portion of the transition zone interconnects the protoxylem poles forming a primary xylem cylinder around the central pith. The collateral bundles pass through the transition zone essentially without change.     

甘草根和根状茎的发育解剖学研究

甘草（ＧｌｙｃｙｒｒｈｉｚａｕｒａｌｅｎｓｉｓＦｉｓｃｈ）实生苗具直根系。其根端原分生组织具三层原始细胞,外层产生表皮和根冠,中层和内层分别产生皮层和中柱。根的初生木质部四原型,由中柱鞘细胞产生第一次周皮。成长根中央的初生木质部由于导管周围薄壁细胞的增殖而被分割成几部分,使导管分子星散分布于薄壁细胞间。实生苗生长到第三年春由于叶节处的更新芽萌发形成最初的根状茎,根状茎顶端的原分生组织由两层原套细胞和一团原体细胞组成。初生结构的分化开始于皮层和髓两部分基本分生组织,而原形成层早期在根状茎横切面上呈连续的分生组织环。以后在环内逐渐分化出原形成层束,由它分化出初生锥管束,根状茎第一次周皮产生于初生韧皮部外方的第五或第六层皮层细胞。     

山茱萸花柱和柱头的发育解剖学及组织化学

山茱萸成熟雌蕊的柱头为干型,具表皮起源的单细胞乳突。在开花后授粉前乳突细胞的顶部发生凹陷,授粉后乳突细胞迅速萎缩。花柱在发育初期为开放型,发育后期花柱道消失,成为一种具特殊结构的闭合型。成熟花柱由表皮、皮层和特殊的引导组织等部分构成,在皮层中贯穿有3条维管束,引导组织的中央则有二列类似腺质的内表皮细胞,该细胞富含蛋白质、核酸和多糖类物质。     

PHYSIOLOGICAL RESPONSES TO RAINFALL IN OPUNTIA BASILARIS (CACTACEAE)

An immediate, marked response to small amounts of rainfall occurs in Opuntia basilaris, despite previous drought conditions. The effect of rainfall is upon plant water potential, which is the single most important parameter influencing stomatal opening, CO₂ assimilation, and organic acid synthesis. Nocturnal stomatal opening is initiated following rainfall, and stomata remain open during the daytime. Decreasing stomatal and mesophyll resistances correlate with increasing rates of nocturnal assimilation of ¹⁴CO₂. Photosynthetic rates of ¹⁴CO₂ assimilation are low, despite high plant water potentials and low stomatal diffusion resistances. The decreased mesophyll resistances and increased rates of nocturnal ¹⁴CO₂ assimilation correlate with the increases of nocturnal efficiency of water use and CO₂ assimilation. The diurnal efficiency of water use and CO₂ assimilation is lower than the nocturnal gas exchange efficiency values.     

DEVELOPMENTAL ANATOMY OF CORALLOID ROOTS IN CYCADS

Coralloid roots of cycads were found to originate endogenously from the pericycle of apogeotropic secondary roots or adventitious roots that have become exposed or nearly exposed to the soil surface. All mature coralloid roots are susceptible to infection by algal endophytes, which seem to enter from the soil through a break in the dermal layers. In the coralloid roots the algae inhabit intercellular spaces in a definite zone that arises from the protoderm, and in which the cells elongate radially following algal infection. The zone is completely surrounded by a persistent rootcap which is interpreted by most authors as a secondary cortex. The secondary cortex was shown to be derived from the rootcap in this investigation.     

ULTRASTRUCTURAL BASIS AND DEVELOPMENTAL CONTROL OF BLUE IRIDESCENCE IN SELAGINELLA LEAVES

The iridescent blue color of several Selaginella species is caused by a physical effect, thin-film interference. Predictions for a model film have been confirmed by electron microscopy of S. willdenowii and S. uncinata. For the latter species iridescence contributes to leaf absorption at wavelengths above 450 nm and develops in environments enriched with far-red (730 nm) light. This evidence supports the involvement of phytochrome in the developmental control of iridescence.     

类根瘤对烟草叶片中叶绿体及其淀粉粒含量的影响

目的：探讨类根瘤对烟草叶片中的叶绿体及其淀粉粒含量的影响。方法：无菌培养烟草再生植株,其中一部分经过一定浓度的2,4－D与豇豆根瘤菌512快生型突变株菌液诱导处理,另外一部分为对照。运用常规电镜技术制作叶片厚切片,通过显微观察,对两组烟草叶片细胞中的叶绿体及其淀粉粒含量进行对比分析。结果：结瘤植株叶片细胞内的叶绿体含量虽然与对照之间无明显差异,但叶片栅栏组织和海绵组织细胞内淀粉粒的含量却均较对照减少,其中前者减少更为明显（P＜0.05)。结论：结瘤烟草叶片内光合产物的大量同化可能与类根瘤的形成有关。     

ULTRASTRUCTURAL CHANGES OF CHLOROPLASTS IN ATTACHED AND DETACHED,AGING PRIMARY WHEAT LEAVES

Degradation of chloroplasts is shown in mesophyll cells of primary leaves of wheat. The sequence of ultrastructural changes in chloroplasts of naturally senescing leaves is compared with that of detached, aging leaves. In chloroplasts of naturally senescing leaves, the first indications of aging are the appearance of osmiophilic globuli and reorientation of the thylakoidal system. The membranes of the grana and intergrana lamellae then become distended and later dissociate into distinct vesicles. Concurrent with these membrane changes, osmiophilic globuli increase in size and number, and the stroma breaks down. Finally, the chloroplast envelope ruptures and plastid contents disperse throughout the cell's interior. In chloroplasts of mesophyll cells in detached, aging leaves, initial changes also include appearance of osmiophilic globuli, but later stages of chloroplast degradation are different. The chloroplast envelope ruptures before the lamellae break down. Swelling of grana and intergrana lamellae is not pronounced and, additionally, the thylakoidal system degenerates without forming vesicles or numerous osmiophilic globuli. These differences in the sequence of chloroplast degradation indicate that naturally senescing leaves rather than detached, aging leaves should be used in studies of chloroplast senescence.     

垂柳花蜜腺的发育解剖学研究

垂柳雌花蜜腺一枚,位于于房与花序轴之间,多呈扁平广卵形,由分泌表皮、泌蜜组织和维管束组成。雄花蜜腺呈基部相连的两枚突起,一枚位于花丝与花序轴之间,基部宽扁,上部棒状;另一枚位于花丝与苞片之间,棒状,仅由分泌表皮和泌蜜组织组成。雌、雄花蜜腺均起源于花托表面2—3层细胞。在蜜腺发育过程中,雌、雄花蜜腺泌蜜组织细胞的液泡发生规律性变化．雌花蜜腺为淀粉型蜜腺,而雄花蜜腺为非淀粉型蜜腺。雌、雄花蜜腺的原宜汁分别由蜜腺维管束韧应部或花丝维管束韧皮部提供,其蜜计最后均由分泌表皮细胞和变态气孔排出。     

GENETIC AND ENVIRONMENTAL DETERMINATION OF LEAF EPIDERMAL ANATOMY IN PUCCINELLIA (POACEAE)

Phenotypic plasticity of anatomical leaf epidermal characters was assessed in the halophytic grass genus Puccinellia, to identify those of potential taxonomic utility. Characters with the greatest taxonomic potential are those that exhibit genetic variation and low plasticity. For the analysis, field-collected clones were divided and grown under a series of moisture and salinity regimes. Genetic variation and plasticity in response to environmental variation were assessed for 39 anatomical characters by analysis of among-clone and among-treatment variation, respectively. Both genetic variation and plasticity are widespread among the characters, and both are detected in greater frequency among continuously variable characters than among discretestate characters. Among continuously variable traits, average cell dimensions exhibit more plasticity than do maximum cell dimensions or ratios that reflect shapes and relative sizes. Among discrete-state characters, plasticity in the occurrence of papillae is found in nonstomatal intercostal cellular ranks, but not in costal or stomatal intercostal ranks. In Puccinellia, anatomical characters are, in general, neither more nor less plastic than those of macromorphology.     

拐枣果序梗的发育解剖学研究

拐枣肉质膨大果序梗的发育过程可划分为前、中、后、末４个时期,前期为初生生长时期,内部结构类似一般双子叶植物茎的初生构造;中期为维管形成层活动时期,产生了不同其茎的次生木质部,由成片木质化的厚壁纤维细胞、一定量的木射线及星散在其中极少数的导管组成;后期为异常分生组织活动时期,初生木质部木薄壁组织及邻近少量髓细胞及邻近少量髓细胞转化为异常分生组织,向外产生切向排列的薄壁细胞,经扩大的切向伸长,使原导管     

蜡梅科植物的叶表皮特征及其在分类上的意义

用扫描电镜和光学显微镜观察了蜡梅科3属5种植物成熟叶片远轴面的表皮特征,认为这些表皮细胞特征和气孔器特征在分类上有比较重要的意义。蜡梅属、夏蜡梅属和美国蜡梅属植物的叶表皮毛均为单细胞毛、非腺毛,上、下表皮细胞均为多边形,垂周壁呈深波状,气孔器均为平列型．这三个属的亲缘关系密切,应该归属于同一个大类群－蜡梅科。这为蜡梅属、夏蜡梅属、美国蜡梅属的分类提供了有用的性状特征。这三个属气孔器的演化趋势为：气孔器在保卫细胞的两极无"T"型加厚到有"T"型加厚,气孔器由单层外拱盖到双层外拱盖．     

木本植物阳生和阴生叶片叶绿体O_2和NO_2~-光还原作用

在有ＰＣＲ和ＰＣＯ环活性抑制剂甘油醛和光合磷酸化解偶联剂ＮＨ４ＣＬ存在下,比较了生长于 ３种 光环境的乔木黧蒴和灌木九节幼苗阳生和阴生叶片叶绿体的Ｏ２和ＮＯ２光还原速率。全自然光下两种 植物阳生叶片的叶绿体Ｏ２的光还原速率最高,占总光合电子传递活性的６６％－６８％,ＮＯ２光还原速率 也有类似趋势占总电子传递的１１％－１５％左右。３６％和１６％自然光下阴生叶片Ｏ２和ＮＯ２光还原 速率及Ｏ２光还原电子传递的比例显著降低,但ＮＯ２光还原电子传递的比例不受影响。与ＮＯ２光还原 相关的叶片ＮｉＲ和ＮＲ活性及ＮｉＲ／ＮＲ活性比也因叶片接受光强度大小而异,随光强减弱,黧蒴的 ＮｉＲ活性降低,九节的ＮＲ活性增高,但黧蒴的ＮＲ活性和九节的ＮｉＲ活性变化未达差异显著性。