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Morphogenesis of Female Reproductive Organs in Carpinus turczaninowii and Ostryopsis davidiana (Betulaceae)


For better understanding of the relationships between genera, the primordium occurrence and morphological developmental process of female inflorescence, cymule and floret in Carpinus turczaninowii Hance and Ostryopsis davidiana Decne. of the Betulaceae were observed under the scanning electron microscope (SEM). Both species were monoecious. Their female inflorescence was a compound spike comprising several cymules arranged helically along an inflorescence axis. Each cymule consisted of two florets and five bracts, i.e., one primary bract and four other secondary ones which were developed from two semi-circular common primordia, respectively. In Carpinus , the adaxial secondary bracts grew slowly, while the abaxial ones grew fast, resulting in the appearance of a wide leafy bract upon maturity. In Ostryopsis , however, both abaxial and adaxial secondary bracts were fully developed, becoming a bladder-like but unclosed involucre when mature. Perianth primordia in both genera were circular. When the ovary became larger and larger, the perigone grew gradually, and finally surrounded and was adnate to the ovary. Some traditional viewpoints on the number of bracts and the orientation of bicarpellate ovary in cymule were clarified based on this study. The cymule bracts were not so many as those observed by Abbe; and the two bicarpellate ovaries were orientated perpendicularly, rather than parallel.

鹅耳枥和虎榛子(桦木科)雌性生殖器官的形态发生
陈之端1  邢树平1 梁汉兴1,2  路安民1

(1. 中国科学院植物研究所系统与进化植物学开放研究实验室,北京100093;
2. 中国科学院昆明植物研究所,昆明650204)

摘要:为了进一步理解类群之间的系统发育关系,在扫描电镜下,对桦木科植物鹅耳枥(Car pinus turczaninowii Hance)和虎榛子(Ostryopsis davidiana Decne .)的雌花序、小花序和雌花的原基形成和发育过程进行了观察.两种植物均具单性花,雌雄同株.其雌花序为复合的穗状花序,每两朵小花构成一个小聚伞花序,多个这样的小花序螺旋排列在一个总花序轴上.小花序由5枚苞片组成,1枚初级苞片,4枚次级苞片.后者分别由两个半环状的共同原基发育而来.鹅耳枥的近轴面次级苞片生长缓慢,远轴面的生长较快,成熟时呈扩展的叶片状;虎榛子的近轴面和远轴面次级苞片均生长较快,成熟时靠合呈囊状.花被原基为环状,花被随着子房的发育而逐渐长大包围子房并与之愈合.研究对前人有关小花序的苞片数目和两个二心皮子房的定位方式等方面的认识作了澄清或纠正.每个小花序的苞片数目不像Abbe观察的那么多;二心皮子房定位方式在鹅耳枥属是互成直角, 而非相互平行.

关键词: 桦木科;鹅耳枥属;虎榛子属;形态发生;苞片;花被;小花序


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