SEEDS AND SYSTEMATICS IN HYDROPHYLLACEAE: TRIBE HYDROPHYLLEAE

Scanning electron microscopic investigation of seed surfaces in tribe Hydrophylleae (Hydrophyllaceae) and seed development in Nemophila indicates the presence of four closely related genera (Ellisia, Hydrophyllum, Nemophila, Pholistoma) and one aberrant genus (Eucrypta), which should probably be transferred elsewhere. Comparative evidence from embryology, morphology, cytology, and palynology is roughly corroborative.     

LEAF DEVELOPMENT IN SCHIZAEA AND ACTINOSTACHYS

Observations on the initiation and growth of the fertile digits and of their assemblages in Schizaea and Actinostachys as well as of the entire frond in S. dichotoma are presented. The leaf of S. dichotoma, although dichotomous in appearance at maturity, goes through a series of dichotomous and lateral ramifications during ontogeny. It is compared with the entire frond (“aerial shoot”) of Psilotum nudum. The sporangiate fructifications of Schizaea develop as their mature form suggests, i.e., by acropetal initiation and development of pinnately arranged digits. The counterpart in Actinostachys, irrespective of fertile digit number, develops as only three pinnae, two lateral and one terminal. It cannot be said, therefore, that the condition in Actinostachys, i.e., the digitate arrangement of fertile parts, is fundamentally the condition which exists in Schizaea but with a very short rachis. The fundamental difference is in pinna number and frequency of dichotomies which establish the final digit number.     

ONTOGENY AND PHYLOGENETIC SYSTEMATICS

Abstract— Dedifferentiation, paedomorphosis, and the insertion and deletion of developmental stages make it impossible to deduce the genealogical hierarchy from only ontogenetic transformation series. Like the outgroup criterion, ontogenetic character precedence is not theory-neutral and to use it to deduce genealogy requires certain assumptions.
If scientists are going to use logically unbeatable theories about the world, they might as well give up natural science and take up religion (Lewontin, 1972: 181).     

LEAF AND APICAL GROWTH CHARACTERISTICS IN TRITICUM

Leaf initiation rate, leaf primordium growth rates, and apical volume growth rates were determined for seedlings of Triticum aestivum cv. Ramona 50 under controlled environmental conditions. Three leaf primordia are present in the caryopsis, and three more leaves are initiated within the first two weeks after germination with a mean plastochron length of 95.5 hr. Volume growth rates of the apical region were determined on six apices which had six primordia each. The mean radial expansion rate was 0.467/plastochron, and the vertical expansion rate was 0.457/plastochron. The volume expansion rate was 1.393/plastochron. The mean volume doubling time was 0.498 plastochrons or 47.1 hr.     

ADAPTIVE LEAF ARCHITECTURE IN EMERGENT AND FLOATING SPARGANIUM

The robust emergent leaves of Sparganium eurycarpum and S. americanum are supported by corner fiber masses and large bundle sheaths, but the thin floating leaves of S. fluctuans and S. minimum have only moderate bundle sheaths. In emergent types heavily photosynthetic diaphragms bearing vascular bundles are separated from each other in the leaf compartments by three lightly photosynthetic diaphragms without bundles, but in floating types only every other heavily photosynthetic diaphragm has a bundle. Palisade chlorenchyma occurs only at aerial surfaces—abaxial and adaxial in emergent leaves, but only adaxial in floating leaves. Extra photosynthetic areas are provided in emergent leaves by concentrations of chlorenchyma in limited areas on interior partitioning walls, while the remainder of the walls is translucent. Since only 25 % of the diaphragms are heavily photosynthetic, and the others essentially transparent because of their diffusely distributed chloroplasts and large intercellular spaces, a sieve effect exists which allows even the interior parts of thick emergent leaves to photosynthesize.     

中国昆虫分类学研究进展

<正> 中国自然条件复杂,昆虫种类繁多,特别是横断山区、青藏高原和云南西双版纳等热带雨林地区昆虫区系丰富多彩,受到国内、外昆虫分类学家的青睐。根据保守估计,中国应有15万种昆虫。中华人民共和国成立前夕我国仅记载20069种昆虫,其中中国人命名的仅204种,绝大多数模式标本及文献资料均散落于国外;分