STUDIES ON THE LEAF OF AMARANTHUS RETROFLEXUS (AMARANTHACEAE): QUANTITATIVE ASPECTS,AND SOLUTE CONCENTRATION IN THE PHLOEM

The vascular system of the leaf of Amaranthus retroflexus L. was examined quantitatively, and plasmolytic studies were carried out on it to determine the solute concentration in cells of the phloem at various locations in the leaf. The proportion of phloem occupied by sieve tubes varies considerably with vein size and leaf size. Collectively, the cross-sectional area of sieve tubes of all tributaries at their points of entry into either a secondary or midvein far exceeds the total cross-sectional area of sieve tubes at the bases of those major veins. In addition, the total volume of sieve tubes in the “catchment area” of a secondary vein is much greater than total sieve-tube volume of the secondary vein itself. The plasmolytic studies revealed the presence of positive concentration gradients in the sieve tubes of the lamina from the minor veins and tips of the secondaries to the bases of the secondaries and from the tip to the base of the midvein. The C₅₀ (the estimated mannitol concentration plasmolyzing, on the average, 50% of the sieve-tube members) was 1.5 m for minor veins and tips of secondary veins and 1.1 m for the bases of secondaries; 1.3 m for the tip of the midvein and 0.6-0.7 m for the midvein in the basal third of the lamina.     

STUDIES ON THE LEAF OF POPULUS DELTOIDES (SALICACEAE): MORPHOLOGY AND ANATOMY

Mature field- and growth-chamber-grown leaves of Populus deltoides Bartr. ex Marsh. were examined with light and scanning electron microscopes to determine their vasculature and the spatial relationships of the various orders of vascular bundles to the mesophyll. Three leaf traces, one median and two lateral, enter the petiole at the node. Progressing acropetally in the petiole these bundles are rearranged and gradually form as many as 13 tiers of vascular tissue in the petiole at the base of the lamina. (Most leaves contained seven vertically stacked tiers.) During their course through the midrib the tiers “unstack” and portions diverge outward and continue as secondary veins toward the margin on either side of the lamina. As the midvein approaches the leaf tip it is represented by a single vascular bundle which is a continuation of the original median bundle. Tertiary veins arise from the secondary veins or the midvein, and minor veins commonly arise from all orders of veins. All major veins–primaries, secondaries, intersecondaries, and tertiaries–are associated with rib tissue, while minor veins are completely surrounded by a parenchymatous bundle sheath. The bundle sheaths of tertiary, quaternary, and portions of quinternary veins are associated with bundle-sheath extensions. Minor veins are closely associated spatially with both ad- and abaxial palisade parenchyma of the isolateral leaf and also with one or two layers of paraveinal mesophyll that extend horizontally between the veins. The leaves of growth-chamber-grown plants had thinner blades, a higher proportion of air space, and greater interveinal distances than those of field-grown plants.     

ON THE ANATOMY AND MORPHOLOGY OF LATERAL BRANCH SYSTEMS OF ARCHAEOPTERIS

A large collection of specimens, consisting primarily of Archaeopteris macilenta, forms the basis for an anatomical and morphological study of the lateral branch systems. Emphasis is placed on the main axes of the branch systems, which are found to be characterized by a variable number of orthostichies of lateral appendages, ranging from 7 to probably 11. The number of orthostichies seems to correspond to the number of ribs of the stele. There may be an equal number of rows of leaves on either side of the plane in which the two rows of lateral branches lie, or one side may have one or two more leaf orthostichies than the other. In all specimens for which both part and counterpart were available, however, there is a greater density of leaves on one side (hypothesized to be the adaxial) than on the other, caused primarily by an apparent abortion of leaf primordia early in development on the side of least density. Leaves and branches occur in the same ontogenetic spiral and in one specimen comprise a ‘phyllotaxis’ of 2/9 and contact parastichies of 5 + 9. On both the main and lateral axes, leaves are characterized by long, decurren bases which essentially ensheath the axrs on which thay are borne. Phyllotaxis and the correlated stelar form apparently vary considerably within Archaeopteris. It is suggested that Archaeopteris was more closely related to the coniferophytes than to any other gymnosperms.     

THE MORPHOLOGY AND ANATOMY OF CALLIPTERIDIUM SULLIVANTI

Leisman , Gilbert A. (Kansas State Teachers Coll., Emporia.) The morphology and anatomy of Callipteridium Sullivanti. Amer. Jour. Bot. 47(4) : 281—287. Illus. 1960.–Previously undescribed pinnules of Callipteridium Sullivanti (Lesq.) Weiss have been studied in Iowa and Kansas coal balls. Conventional peel techniques revealed the anatomy while deliberately fracturing the coal ball revealed morphological features. Epidermal studies were also conducted after macerating small portions of the coal ball. Evidence indicates that these pinnules were borne on Myeloxylon petioles. Arguments are advanced for removing this species from the genus Alethopteris and returning it to Callipteridium.     

STUDIES OF PALEOZOIC SEED FERNS: ANATOMY AND MORPHOLOGY OF MICROSPERMOPTERIS APHYLLUM

The discovery of numerous specimens of the monostelic pteridosperm genus Microspermopteris in Pennsylvanian coal ball petrifactions from the Lewis Creek and What Cheer localities provides additional information about the anatomical and morphological variability within the genus. Specimens are now known up to 1.1 cm in diam that bear epidermal appendages in the form of variously-shaped trichomes. The external surface of the stem is further ornamented by longitudinal flaps of cortical tissue. Petioles exhibiting a single C-shaped vascular strand with abaxial protoxylem are produced in a 2/5 phyllotaxy. Large petiole bases that clasp the stem produce primary pinnae alternately. The presence of axillary branching appears similar to that reported in Callistopliyton and Lyginopteris. Triarch to polyarch adventitious roots, some with secondary tissues, are produced at both nodal and internodal regions. Of the currently recognized monostelic seed fern genera, Microspermopteris is most similar to Heterangium. Information is presented that supports current ideas regarding the evolution of the gymnospermic eustele from protostelic Devonian ancestors.     

SYSTEMATIC STUDIES IN THE LEAF ANATOMY OF PALM GENUS SYAGRUS

A systematic survey of the leaf anatomy of 51 taxa in the palm genus Syagrus was made. Cross sections of the middle pinnae of each taxon were embedded, cut, stained, and mounted on slides. Criteria used to distinguish species were based mainly on differences in the laminar surface and hypodermis: frequency and location of various sized veins; frequency, shape, and location of nonvascular fibers; size and shape of midrib and main vascular bundle; and size and shape of expansion cell tissue. The included key to the species employs mostly these characteristics. Each taxon is listed under subgenera and sections in the order presented in a previous article, where gross morphology was used as the basis of classification. Relationships between species of each subgenus and section are discussed in terms of the original arrangement of each group and needed changes. It is significant that certain evolutionary sequences have become unfolded which were not apparent by use of morphological characters alone. Although all relationships have not been completely worked out, this survey has resulted in a revision of my original classification of the genus Syagrus and at the same time has also corroborated certain alignments of species previously based on gross morphology.     

红色角毛虫的形态学和形态发生过程的研究

观察并描述了上海采集到的红色角毛虫的形态结构和形态发生过程。发现形态发生时虫体分别于前、后两个区域发生前、后两个口围带原基,并且由同一个体分裂而成的前,后两个仔虫内,额、腹、横棘毛和缘棘毛的分化并不完全相同,以至造成两个仔虫上棘毛的数目和缘棘毛的列数有明显差异。根据红色角毛虫的形态结构及其形态发生中的一些不够稳定的特点,推测它可能是一种还处于分化中的腹毛类纤毛虫。     

SOME EFFECTS OF NITROGEN NUTRITION ON THE MORPHOLOGY AND ANATOMY OF MARROW-STEM KALE

Marrow-stem kale plants grown on plots receiving frequent additions of sulphate of ammonia showed a 40% increase in length of internode and a 25% increase in number of nodes per plant, and the leaf size was increased by between 50 and 70% over plants in plots receiving no N fertilizer. Leaves of kale continue to increase in area until they turn yellow, and the high N leaves showed a greater rate of increase in area at every stage in the life of the leaf.
Various features of leaf structure, such as stomatal index, and thickness of palisade and mesophyll, were unaffected by N treatment. The size of the epidermal cells of the leaves was very variable, and although the high N leaves showed a 12% increase in area per epidermal cell over the low N leaves, this difference is not statistically significant. The increased area of the high N leaves can therefore be attributed mainly to increased cell division during the life of the leaf. Only a very slight increase in rate of cell division is necessary to produce the observed effect.
The greater leaf area of the high N plants can be attributed mainly to increased size of individual leaves, but there was also a significantly greater number of living functional leaves per plant on the high N plants; at 23 weeks from sowing the high N plants had an average of 13.4 living leaves, while the low N plants had only 11.7 living leaves per plant.
There was an appreciable degree of N succulence in the high N kale leaves, which showed a 2% greater moisture content than the low N leaves.
A seasonal drift in epidermal cell size, palisade thickness, and total leaf thickness, is shown to be fully significant, statistically. Marked variations in stomatal frequency are barely significant at the 5% level.     

STUDIES OF PALEOZOIC FERNS. THE MORPHOLOGY,ANATOMY, AND TAXONOMY OF ANKYROPTERIS GLABRA

Eggert , Donald A. (Yale U., New Haven, Conn.) Studies of Paleozoic ferns. The morphology, anatomy, and taxonomy of Ankyropteris glabra. Amer. Jour. Bot. 46(7): 510–520. Illus. 1959.—This is a morphological and taxonomic study of the American specimens of Ankyropteris, with the exception of A. hendricksi, that previous to this time have been referred to A. grayi, originally a Lower Carboniferous species from England, and to A. glabra, a Middle-Pennsylvanian form from Booneville, Indiana. The problem of the separation of these two closely allied species is discussed, and the original criteria for separation are questioned, on the basis of four specimens described in the present paper. The specimens are from West Mineral, Kans. and Shuler Mine in Iowa. They all have been referred to A. glabra and show extreme plasticity of several features of the plant that is correlated with the size of the stem. The major points of difference between A. glabra and A. grayi are now thought to be the presence of distantly spaced nodes in A. glabra, in contrast to closely spaced ones in A. grayi, and the presence of a small amount of mixed tissue in the stele of A. glabra, compared to a large amount in A. grayi. Well preserved axillary branches were found, whose morphology is typically that of the parent stem. It is suggested that the axillary branches were well developed in the species, and that, therefore, several orders of branching may be present in the American material. Successive orders of branching show diminution and simplification which is interpreted as an expression of the presence of determinate growth in the cauline systems of the plant, an ontogenetic pattern that is not commonly found in living forms.