bluuebunny/crossref_metadata_2025 huggingface dataset:
RACIAL DIFFERENCES IN WIDESPREAD SPECIES, WITH SPECIAL REFERENCE TO THOSE COMMON TO JAPAN AND NORTH AMERICA
Authors: Hara Hiroshi
Published: January 2018

Hara, Hiroshi. (U. Tokyo, Hongo, Tokyo.) Racial differences in widespread species, with special reference to those common to Japan and North America. Amer. Jour. Bot. 49(6): 647–652. Illus. 1962.—Various data on morphological and chromosomal differences in widespread taxa mainly common to Japan and North America are presented. The examples given here are the groups of Anemone hepatica, Rosa acicularis, Lathyrus palustris, Ledum palustre, Triglochin maritimum, Adoxa moschatellina, Iris setosa, Cryptotaenia canadensis, etc. It is manifest that the mode of geographical variation is different in the several plant groups concerned, so its significance is not uniform, and different groups have to be treated in different ways. In Anemone hepatica, tetraploid plants have been found only in Japan, and the pattern of their pollen grains is different from that of common diploids. In several groups, highest polyploids have been recorded in Japan, while many diploid species also occur there. These facts can be explained by the antiquity of the flora as well as the complicated past history and the diversity of the habitats under the present environmental conditions of Japan.
FOSSIL WOOD OF ROBINIA AND GLEDITSIA FROM THE TERTIARY OF MONTANA
Authors: Prakash U. , Barghoorn E. S. , Scott R. A.
Published: January 2018

Prakash, U., E. S. Barghoorn, and R. A. Scott. (Harvard U., Cambridge, Mass.) Fossil wood of Robinia and Gleditsia from the Tertiary of Montana. Amer. Jour. Bot. 49(7): 692–696. Illus. 1962.—Fossil woods representing 2 genera of the Leguminosae, Robinia Linnaeus and Gleditsia Clayton, have been identified from Tertiary beds in southern Montana. These woods are noteworthy owing to their exceptionally fine structural preservation and from the standpoint of their paleogeographical distribution. Neither genus now lives in the region of Montana.
CERCIDIUM FLORIDUM SEED COAT, LIGHT AND ELECTRON MICROSCOPIC STUDY
Authors: Scott Flora Murray , Bystrom B. G. , Bowler E.
Published: January 2018

Scott, Flora Murray, B. G. Bystrom, and E. Bowler. (U. California, Los Angeles.) Cercidium floridum seed coat, light and electron microscopic study. Amer. Jour. Bot. 49(8): 821–833. Illus. 1962.—The structure of the seed coat of the desert tree Cercidium is typical of the family Leguminosae, but the inner integument is mucilaginous. The characteristic palisade cells of the epidermis and the many‐armed cells of the mucilaginous zone are discussed in detail. The minute wax rodlets on the surface of the young seed fuse later into a film of wax. The epidermal palisade cells are polygonal in transection and the walls are strengthened by cellulose flanges. The palisade cells are enclosed in a thin suberin‐like sheath which connects with the film which lines all air‐filled intercellular spaces in the outer integument. Plasmodesmata extend from the protoplast through the subcuticular zone to the cuticle and also interconnect with adjacent cells through numerous pits in the interflange areas of the main wall. The cells of the inner integument are many‐armed. Intercellular spaces at all stages of growth observed are occluded with mucilage; nevertheless, they are lined with a suberin‐like film similar in reaction to that of the air‐filled intercellular spaces of the outer integument. The distribution of wall materials and ergastic substances was determined by microchemical tests. For electron microscopic study, the epidermis and the mucilaginous zone were fragmented ultrasonically, after chemical treatment when necessary. Cuticular fragments, frequently polygonal in outline, are dense to the electron beam at photographic illumination. When exposed to the electron beam, full‐strength, volatile components are driven off and condense on other wall fragments or on substrate. Unique structures occur in the subcuticular zone, termed here, collar, cone and paddle structure. The basic material of the cell wall as a whole is cellulose impregnated with matrix materials, mainly non‐cellulosic polysaccharides. In addition, lipid‐like substances are conspicuous particularly in the flanges of the palisade cells. Under the electron beam, full‐strength, these substances volatilize and leave the flanges with a blistered outline except in the region of the light line. The volatile substances may be absent from this zone or the microfibrillar structure may prevent distortion. The microfibrillar pattern throughout the length of the flanges is dominantly parallel, but a change to reticulate arrangement occurs in the light‐line region. Numerous pits mark the paths of the plasmodesmata in the subcuticular zone and also through flange and interflange areas of the wall. The dominant microfibrillar pattern in the mucilage cells is reticulate in young and old cells, except for helical orientation in extending arms. Pits occur on arm ends but are infrequent elsewhere. The loose microfibrillar structure presumably allows continuous secretion of mucilage.
CYTOGENETICS OF TAGETES JALISCENSIS x T. ERECTA
Authors: Towner Joseph W.
Published: January 2018

Towner, Joseph W. (U. California, Los Angeles.) Cytogenetics of Tagetes jaliscensis X T. erecta. Amer. Jour. Bot. 49(10): 1064–1067. Illus. 1962.—Although Tagetes jaliscensis and T. erecta are morphologically very distinct, the F1 hybrid between them had normal meiosis (12 bivalents) and was fertile. Segregation in F2 was undisturbed for marker genes on 4 pairs of chromosomes. These facts suggest that T. jaliscensis, like T. erecta, is an A‐genome diploid (genome formula A2A2). From plant morphology, the A‐subgenome of amphiploid T. patula is regarded as more likely derived from T. erecta than from T. jaliscensis. In T. jaliscensis X erecta F2, disk corolla anthocyanin (R = red) from T. jaliscensis segregated as a simple dominant over the absence of anthocyanin from T. erecta. A chlorophyll defect was determined by duplicate factor recessives. Tubular ray flowers (tu = tubular) segregated as a simple recessive to normal flat rays in the interspecific F2 and in T. erecta.
STUDIES OF NECROTIC LESIONS IN CORN STALKS
Authors: Littlefield Larry J. , Wilcoxson Roy D.
Published: January 2018

Littlefield, Larry J., and Roy D. Wilcoxson. (U. Minnesota, St. Paul.) Studies of necrotic lesions in corn stalks. Amer. Jour. Bot. 49(10): 1072–1078. Illus. 1962.—In 3‐day‐old necrotic lesions in corn stalks caused by Fusarium graminearum, ground parenchyma cells were discolored and small amounts of a dark substance were present in the cells. The walls of phloem cells were also slightly discolored and a small amount of dark substance was present in the xylem cells. In older lesions the discoloration of parenchyma and phloem cells was more intense; many of the cells contained occluding substances; many phloem protoplasts collapsed, and xylem cells were partially to completely occluded. The occluding substance filling the cells appeared to be translocated from the lesion into the vessel elements extending beyond the lesion so that the bundles appeared as long, dark streaks in the stalk. The occluding substance in xylem, but not in phloem or parenchyma, stained with ruthenium red, a result indicating presence of pectin. Pectinase, however, did not remove the occluding substance. The pectinase dissolved the parenchyma cells in healthy tissues but not in the necrotic lesions. Necrosis in naturally infected plants began as small lesions, but the parenchyma cells quickly dissolved leaving the vascular bundles free of ground parenchyma. No occlusions were found in the central vascular system; a few xylem cells in the peripheral vascular system were occluded with the same substance observed in artificially inoculated plants. Phloem was entirely destroyed by the pathogen. The necrosis prevented upward movement of dye solution in the stalk, but did not measurably affect transpiration, probably because the lesions were not large. Yield was reduced in plants when lesions involved more than 50% of the tissue in inoculated internodes. Smaller lesions had no effect on yield.
A NEMATODE‐CAPTURING PHYCOMYCETE WITH DISTALLY ADHESIVE BRANCHES AND PROXIMALLY IMBEDDED FUSIFORM CONIDIA
Authors: Drechsler Charles
Published: January 2018

Drechsler, Charles. (U.S.D.A., Plant Industry Sta., Beltsville, Md.) A nematode‐capturing phycomycete with distally adhesive branches and proximally imbedded fusiform conidia. Amer. Jour. Bot. 49(10): 1089–1095. Illus. 1962.—A fungus newly described as Acaubpage pectospora, though some uncertainty remains as to its taxonomic relation, captures nematodes (Bunonema sp.) by means of small sticky knobs disposed on the surface of the substratum, where they are supported on upcurved tips of continuous subsurface hyphae and of short subsurface hyphal branches. After effecting capture, the knob grows out at its apex and produces a clavate or dolioform appressorium together with an infection‐bulb broadly intruded into the animal. From the infection‐bulb assimilative hyphae are extended lengthwise through the fleshy interior. Asexual reproduction ensues through development of solitary, colorless, slenderly fusiform conidia, gradually but markedly tapered toward both ends, mostly about 200 μ long and 11 μ wide. Each conidium is connected with a subsurface hypha by an isthmus about 1 μ wide. While its cornuate proximal end is securely imbedded in the substratum, the conidium for about seven‐eights of its length extends erectly into the air, thereby contrasting with the submerse elongated “gemmae” of Zoophagus tentaclum and of some other robust rotifer‐capturing fungi that have been referred to Z. insidians.
DIFFUSION THROUGH STOMATES
Authors: Ting Irwin P. , Loomis Walter E.
Published: January 2018

Ting, Irwin P., and Walter E. Loomis. (Iowa State U., Ames.) Diffusion through stomates. Amer. Jour. Bot. 50(9): 866–872. Illus. 1963.—It is shown that the rule that diffusion through isolated, small pores is proportional to the diameter rather than the area of the pores is valid for pores of diameters as small as 20 μ, and that the curve extends to the origin at zero diameters, indicating that the law is effective throughout the range of stomatal sizes. Suggestions that an elliptical pore will be relatively more effective in diffusion than a circular one and that diffusion is concentrated at the periphery of the pore are not supported by experimental evidence and are physically improbable. Brown and Escombe's conclusion that there is no interference in the diffusion through the individual pores of a multiperforate membrane if the pores are spaced 10 diameters apart is not valid for diffusion through the stomates of a leaf. With pores of 200 μ and less spaced 10 diameters apart, interference increases rapidly with a smaller size and larger number of pores. As a result, the diffusion through a membrane with pores 19 μ in diameter and 190 μ apart was the same as that through a membrane with pores 132 μ in diameter and 1.32 mm apart, although the calculated capacity of the first membrane was 7 times that of the second. The diffusion of water vapor through multiperforate membranes with pores spaced 10 diameters apart has an apparent maximum of 65–70% of the diffusion through an open tube. Calculations of the effect of partial closing of stomates, using Verduin's equation for interference between pores, indicate that the theoretical diffusion capacity of 10 μ stomates spaced at 10 diameters would be increased several times by closing to an average diameter of 5 μ. This increase illustrates the dominant effect of interference in diffusion through small, closely spaced pores. Calculated diffusion through these stomates would not be decreased until they were more than 95% closed. It is concluded that stomatal opening will have no important effect on diffusion from or into a leaf until the stomates are essentially closed.
THE MORPHOLOGY OF THE INFLORESCENCE OF RAGWEEDS (AMBROSIA‐FRANSERIA : COMPOSITAE)
Authors: Payne Willard W.
Published: January 2018

Payne, Willard W. (U. Michigan, Ann Arbor.) The morphology of the inflorescence of ragweeds (Ambrosia‐Franseria: Compositae). Amer. Jour. Bot. 50(9): 872–880. Illus. 1963.—The ragweeds possess an inflorescence which is highly modified in relation to anemophily. Several trends from primitive to specialized character expressions may be seen in the morphology of the unisexual capitula and florets. An evolutionary scheme is presented whereby the catkinlike, acropetally maturing, staminate spike and the sessile, centrifugally developing, fruiting involucre cluster are derived from basic inflorescence types within the Compositae. Morphological evidence suggests that: (1) the taxa Ambrosia and Franseria should be combined under the older generic name Ambrosia; (2) the ragweeds and their relatives as a group appear to occupy a position intermediate between the Heliantheae and Anthemideae, as currently delimited within the Compositae.
MORPHOLOGICAL AND EMBRYOLOGICAL STUDIES ON THE LEMNACEAE. II. THE ENDOSPERM AND EMBRYO OF LEMNA PAUCICOSTATA
Authors: Maheshwari Satish C. , Kapil R. N.
Published: January 2018

Maheshwari, Satish C., and R. N. Kapil. (U. Delhi, Delhi, India.) Morphological and embryological studies on the Lemnaceae. II. The endosperm and embryo of Lemna paucicostata. Amer. Jour. Bot. 50(9): 907–914. Illus. 1963.—The first division of the primary endosperm nucleus is followed by wall formation. The second division is also transverse so that a longitudinal row of 4 cells is formed. The next 2 divisions are vertical and result in a 16‐celled endosperm arranged in 4 tiers of 4 cells each. The development is, therefore, Cellular (even in L. minor) from the beginning and not Helobial, as reported earlier. The embryogeny conforms to the Asterad type. The radicle is absent in the mature embryo. Comparative studies of the structure of the endosperm and embryo furnish strong evidence in favor of a relationship of the Lemnaceae with the Araceae rather than with the Helobiales.
THE VASCULAR CAMBIUM AND XYLEM DEVELOPMENT IN HIBISCUS LASIOCARPUS
Authors: Cumbie B. G.
Published: January 2018

Cumbie, B. G. (U. Missouri, Columbia.) The vascular cambium and xylem development in Hibiscus lasiocarpus. Amer. Jour. Bot. 50(9): 944–951. Illus. 1963.—Circumferential growth of the vascular cambium, as determined primarily by an analysis of the secondary xylem, in Hibiscus lasiocarpus, an herbaceous dicotyledon, occurred through both radial and oblique anticlinal divisions. Divisions to produce segments were less frequent. Although the fusiform initials usually elongated somewhat between successive divisions, this accounted for very little increase in circumference of the cambium. A fusiform initial underwent a specific pattern of anticlinal divisions, determined primarily by its length, at the beginning of cambial activity. There was no loss of fusiform initials, except by ray formation. Most new rays originated only after considerable secondary xylem had been formed. The findings are discussed in relation to circumferential growth of the vascular cambium in woody dicotyledons.
THE CELL WALL OF SCENEDESMUS QUADRICAUDA
Authors: Blsalputra T. , Weier W. e.
Published: January 2018

Bisalputra, T., and T. E. Weier. (U. California, Davis.) The cell wall of Scenedesmus quadricauda. Amer. Jour. Bot. 50(10): 1011–1019. Illus. 1963.—Fine structure of the cell wall of Scenedesmus quadricauda fixed in both KMnO4 and osmium tetroxide is described. The cell wall consists of 3 layers: the inner cellulosic layer which delimits individual cells; the outer pectic layer which binds the cells of the coenobium together; and a thin middle layer, bounded by membranes on either side, which is electron‐dense in osmium‐fixed material but of medium electron density in KMnO4. The structure of the outer pectic layer is similar in both fixatives; it consists of a hexagonal network of electron‐dense material on the surface, and a system of tubules or “props” which radiate out from the middle layer of the wall to support the net. The pectic layer appears in the daughter coenobia before their liberation from the parent colony.
LENGTH OF THE LIGHT‐DARK CYCLE AND PLANT GROWTH
Authors: Tukey H. B. , Ketellapper H. J.
Published: January 2018

Tukey, H. B., Jr., and H. J. Ketellapper. (California Inst. Tech., Pasadena.) Length of the light‐dark cycle and plant growth. Amer. Jour. Bot. 50(2): 110–115. Illus. 1963.—It has been shown that the length of the light‐dark cycle which causes maximal growth of tomato, pea, peanut, and soybean plants is close to 24 hr for cycles consisting of equal periods of light and darkness. The exact optimum for tomato plants was determined by temperature; the optimal cycle length was 20 hr at 30 C and 27–30 hr at 14 C. Such an interaction between temperature and cycle length was not found in pea plants, because peas were less sensitive to cycle length than peanuts, tomatoes, and soybeans and did not respond to changes in cycle length of 2–3 hr. The response to cycle length was not influenced by the conditions in which the seedlings had been raised prior to the treatment. Seedlings raised in a 16‐hr light, 8‐hr dark regime responded in the same manner as those raised in continuous light. The response to cycle lengths of 18, 24, 36, and 48 hr was not changed qualitatively by the temperature during the growth determination. Small changes in cycle length had no characteristic effects on the rates of photosynthesis, respiration or stem elongation. Stem elongation showed a rapid and initial increase in rate when the light was turned off. It was concluded that plants possess an endogenous time‐measuring device with a period of 24 hr. For maximal growth to occur the external periodicity must be synchronized with the endogenous period of the plant. Efforts to obtain direct evidence for this hypothesis were not successful since no overt rhythms could be found in tomato plants.
CHROMOSOME NUMBERS IN COMPOSITAE. III. SENECIONEAE
Authors: Ornduff Robert , Raven Peter H. , Kyhos Donald W. , Kruckeberg A. R.
Published: January 2018

Ornduff, Robert (Duke U., Durham, N. C), Peter H. Raven, Donald W. Kyhos, and A. R. Kruckeberg. Chromosome numbers in Compositae. III. Senecioneae. Amer. Jour. Bot. 50(2): 131–139. Illus. 1963.—Chromosome counts are reported for 75 taxa of tribe Senecioneae (Compcsitae) and are listed with a generic summary of previous counts in the tribe. First counts are reported for Bedfordia, Crocidium, Dimeresia, Gamolepis, Lepidospartum, Luina, Peucephyllum, Telradymia, and the first definite count recorded for Euryops. New numbers are added to those previously known in Arnica and Psathyrotes. Intraspecific differences in ploidy‐level are reported in 4 North American species of Senecio. Although chromosome numbers are useful as an aid in delimiting some genera of Senecioneae, they are of little use in circumscribing genera peripheral to Senecio, primarily because of the great range of chromosome numbers of that genus. Chromosome numbers support suggestions based on morphological considerations that genera such as Crocidium and Dimeresia do not belong in Senecioneae, whereas chromosome number and morphology of the plants virtually prohibit the removal of such genera as Peucephyllum, Lepidospartum, and Telradymia from Senecioneae, despite the suggestions of several recent authors. It is proposed that the base number for the tribe is 10 and that the tribe originated in the Old World, with subsequent widespread migration and diversification.
THE CAMBIUM AND SEASONAL DEVELOPMENT OF THE PHLOEM IN PYRUS MALUS
Authors: Evert Ray Franklin
Published: January 2018

Evert, R. F. (U. Wisconsin, Madison.) The cambium and seasonal development of the phloem in Pyrus malus. Amer. Jour. Bot. 50(2): 149–159. Illus. 1963.—The cambium in apple consists of several layers of cells at all times, and practically all cambial cells divide periclinally one or more times before undergoing differentiation. The cambial initials do not seem to be in a uniform, uniseriate layer. Judged by collections made during 2 seasons (August, 1958–October, 1960), the seasonal cycle of phloem development is as follows. Early in April, cells in the outer margin of the cambial zone begin to differentiate into sieve elements. At approximately the same time, activity (division) commences throughout the cambial zone. By the end of July or early August, sieve‐element differentiation is completed. Cessation of function begins in either late September or in October with the formation of definitive callose on the sieve areas of sieve elements in the outer margin of the functional phloem. By late November, all sieve elements are devoid of contents and most of their companion cells collapsed. Phloem differentiation precedes xylem differentiation by approximately a month and a half; xylem and phloem differentiation cease almost simultaneously; and fiber‐sclereid development is coincident with the period of maximal xylem differentiation.
STUDIES OF PALEOZOIC FERNS: THE FROND OF ANKYROPTERIS GLABRA
Authors: Eggert Donald A.
Published: January 2018

Eggert, Donald A. (Southern Illinois U., Carbondale.) Studies of Palerzoic ferns: The frond of Ankyropteris glabra. Amer. Jour. Bot. 50(4): 379–387. Illus. 1963—The major features of the frond of A. glabra are described on the basis of preserved parts found in Middle Pennsylvanian coal ball material from Illinois. The frond is planated and has well‐developed foliar laminae. Primary pinnae arise from the petiole in 2 alternating series, and secondary pinnae arise in a similar fashion from the primary pinnae. Foliar laminae occur on the secondary pinnae and have dichotomous venation. The xylem of the petiole has a diupsilon configuration in the lower part of the axis, while higher in the petiole the xylem forms a strand resembling that of the European species A. westfaliensis. The xylem strands of the primary pinnae arise from the adaxial antennae of the petiolar vascular strand as somewhat C‐shapcd bodies and develop antennae and become H‐shaped at higher levels. A gap occurs in the antenna of the petiole vascular system above the level of departure of the primary pinna trace. Terete vascular strands occur in the secondary pinna axes which arise from the adaxial antennae of the xylem of the primary pinnae. The foliar laminae are relatively thin, have an irregular outline, and their histology is like that found in many living ferns. The frond of A. glabra illustrates that leaf evolution had progressed in at least one species of the coenopterid family Zygopteridaceae to the extent that an essentially 2‐dimensional frond of modern aspect, and with well‐developed foliar laminae, was present by Middle Pennsylvanian time.
MULTIPLE ALLELES AT THE INCOMPATIBILITY LOCUS IN THE MYXOMYCETE DIDYMIUM IRIDIS
Authors: Collins O'Neil Ray
Published: January 2018

Collins, O'Neil Ray. (Queens Coll., New York City.) Multiple alleles at the incompatibility locus in the Myxomycete Didymium iridis. Amer. Jour. Bot. 50(5): 477–480. 1963.—Working with 2 isolates of Didymium iridis, from Honduras and Panama, respectively, it was shown that each isolate possesses a pair of incompatibility factors. On the basis of results from inter‐isolate crosses, one pair was designated A1 A2 and the other A3 A4 to indicate that these factors actually constitute a series of multiple alleles at a single locus.
PHASE‐CINEMICROGRAPHIC OBSERVATIONS ON CULTURED CELLS. I. FORMATION OF TRANSVACUOLAR STRANDS IN EUPHORBIA MARGINATA
Authors: Mahlberg Paul G. , Venketeswaran S.
Published: January 2018

Mahlberg, P.G., and S. Venketeswaran. (U. Pittsburgh, Pittsburgh, Pa.) Phase‐cinemicrographic observations on cultured cells, I. Formation of transvacuolar strands in Euphorbia marginata. Amer. Jour. Bot. 50(6): 507–513. Illus. 1963.—Living and vacuolated plant cells frequently possess a network of transvacuolar strands. In the dynamics of the strand system, individual strands can be observed to disappear as well as to become re‐formed from the cytoplasm in characteristic patterns. A strand can disappear from the reticulum either by total contraction, or by fusion of the entire length with adjacent cytoplasm. New strands are delimited from the surrounding cytoplasm when vacuoles become evident in an aggregated mass of the cytoplasm within a localized portion of a cell. During subsequent movements of the new strands, the vacuoles enlarge and become confluent with the total vacuolar content of the cell. Streaming within the new strands becomes uni‐ or bi‐directional in contrast to a multi‐directional pattern within the aggregated cytoplasm. The formation of new strands is associated with an increase in the cytoplasmic membrane area in contact with the vacuole. The membrane is interpreted as possessing a proteinaceous lattice structure. Changes in area and movement of the strands are interpreted to be reversible involving alteration of the structural proteins, their addition or removal, from the lattice of the membrane.
DIMENSIONAL AND ZONATIONAL VARIATION IN DORMANT SHOOT APICES OF PINUS PONDEROSA
Authors: Tepper Herbert B.
Published: January 2018

Tepper, H. B. (State U. Coll. of Forestry, Syracuse, New York.) Dimensional and zonational variation in dormant shoot apices of Pinus ponderosa. Amer. Jour. Bot. 50(6): 589–596. Illus. 1963.—The dimensions and zonation of the apices of the dormant leader and terminal branches in 8 ponderosa pine trees are compared. Apices in upper positions in the crown tend to have larger diameters than those in lower positions. While no consistent trend in the variation of the height of the shoot apex could be demonstrated, the height/diameter (H/D) ratio of the apex increases in progressively lower positions in the crown. Correlation analysis of the pooled data from all trees indicates there is no correlation between height and diameter, but that there is a significant correlation between H/D ratio and diameter of the apex. The H/D ratio of apices of small diameter is larger than that in those of large diameter. While the cytohistological zonation of apices in all positions in the crown is similar, apices of largo diameter have a more extensive distal zone, rib meristem zone and peripheral zone than those of small diameter.
RELATION OF DL‐HOMOCYSTEINE, DL‐METHIONINE, AND METHYL DONORS TO THE APHANOMYCES ROOT ROT OF PEAS
Authors: Davey C. B. , Papavizas G. C.
Published: January 2018

Davey, C. B., and G. C. Papavizas. (Crops Res. Div., ARS, USDA, Beltsville, Md.) Relation of dl‐homocysteine, dl.‐methionine, and methyl donors to the Aphanomyces root rot of peas. Amer. Jour. Bot. 50(1): 67–72. 1963.—dl‐Homocysteine, a compound lacking a methyl (CH3) group, completely prevented Aphanomyces root rot of peas, whereas several CH3 donors (betaine, choline, dimethyl‐β‐propiothetin chloride, S‐methylmethionine) did not. dl‐Homocysteine was taken up by pea plants from nutrient solution and converted to methionine. The methylation of dl‐homocysteine in pea tissue occurred without an exogenous source of labile CH3 groups. More d‐ than l‐methionine was taken up by the plants and more methionine of both forms was taken up when methionine served as the sole sulfur source than when it was supplemented with sulfate. dl‐Methionine sulfoxide but not dl‐methionine sulfone was converted to methionine in pea tissues. Methionine derived from dl‐methionine sulfoxide was proportionately more abundant in the aerial portions of the plants.
INCREASE IN CELL WALL SURFACE AREA DURING ENLARGEMENT OF CAMBIAL DERIVATIVES IN ABIES CONCOLOR
Authors: Wilson Brayton F.
Published: January 2018

Wilson, Brayton F. (U. California, Berkeley). Increase in cell wall surface area during enlargement of cambial derivatives in Abies eoncolor. Amer. Jour. Bot. 50(1): 95–102. Illus. 1963.— Dimensions of fusiform cells (tracheids and sieve cells) and ray cells were measured from samples of the 1960 xylem and phloem increment of 5 trees felled at monthly intervals from April through July, 1960. Calculations using these measurements gave the magnitude, direction and rate of increase in cell wall surface area during enlargement. Although 14 times more tracheids than sieve cells were produced, both cell types enlarged mostly in a radial direction (up to 400%) at the same rate (20–33 × 103μ2 wall surface area/day) to the same final size. Fusiform cambial cells doubled their wall area between successive periclinal divisions. Calculations showed that ⅞ of this increase was in the radial walls of the daughter cells at a rate comparable to that in enlarging tracheids and sieve cells; the other ⅞ was from cell plate formation at an estimated rate of 187–327 × 103μ2/day. Enlargement of derivatives in the radial direction largely determined the amount of increase in wall area. Besides radial enlargement, tracheids also elongated (up to 13%) and phloem cells enlarged tangentially (sieve cells up to 36%; pholem ray cells up to 60%). The relationships of enlarging tracheids and xylem ray cells are discussed, and it is suggested that slippage may occur between the developing walls.
TRIASSIC ROOTS FROM THE PETRIFIED FOREST NATIONAL PARK
Authors: Daugherty Lyman H.
Published: January 2018

Daugherty, Lyman H. (U. Michigan, Ann Arbor.) Triassic roots from the Petrified Forest National Park. Amer. Jour. Bot. 50(8): 802–805. Illus. 1963.—Araucariorhiza joae, a new genus and species of Triassic roots, is described. The description includes the root tip with a columella type embryonic region, the secondary roots, the small tertiary roots, and a discussion in regard to the relationship of this form genus.
SPORE GERMINATION AND CARBON METABOLISM IN FUSARIUM SOLANI. II. ENDOGENOUS RESPIRATION IN RELATION TO GERMINATION
Authors: Cochrane Vincent W. , Cochrane Jean Conn , Collins Calden B. , Serafin Frank G.
Published: January 2018

Cochrane, V. W., Jean C. Cochrane, C. b. Collins, and F. G. Serafin. (Wesleyan U., Middletown, Conn.) Spore germination and carbon metabolism in Fusarium solani. II. Endogenous respiration in relation to germination. Amer. Jour. Bot. 50(8): 806–814. Illus. 1963.—Endogenous oxygen uptake by ungerminated macroconidia of Fusarium solani f. phaseoli is more than doubled by exogenous ammonium ion and is increased about 7‐fold by germination. The respiratory quotient is halved by the provision of ammonia, which has essentially no effect on the endogenous formation of carbon dioxide. Stimulation by azide and 2,4‐dinitrophenol suggests that the supply of phosphate acceptors regulates the rate of endogenous respiration. Mercurials poison the endogenous respiration, cyanide accelerates it, and iodoacetate, arsenite, fluoride, and chelating agents have little effect. Respiration is little affected by changes in pH, external phosphate, oxygen concentration, and spore density, within the limits tested. Spore lipid concentration is increased by cultivation in a high‐glucose medium, but this variation in lipid content of spores docs not affect the endogenous Qo2, nor does a high lipid content abolish the requirement for exogenous carbon for germination. Lipid utilization during endogenous respiration accounts for 37% of the loss in dry weight; lipid is also utilized during germination, but such utilization amounts to only about 5% of the carbon requirement. Neither mannitol nor nitrogenous compounds are significant substrates of endogenous respiration. The oxidation of the exogenous substrates tested does not measurably affect the concomitant rate of endogenous respiration. It is proposed that endogenous respiration can contribute to the synthetic processes of spore germination, although quantitatively insufficient to support germination without exogenous carbon. It is also questioned whether the respiratory quotient is an adequate index of the substrate of endogenous respiration.
IDENTIFICATION OF THE ANCESTRY OF AN AMPHIPLOID VIOLA WITH THE AID OF PAPER CHROMATOGRAPHY
Authors: Stebbins G. L. , Harvey B. L. , Cox E. L. , Rutger J. N. , Jelencovic G. , Yagil E.
Published: January 2018

Stebbins, G. L., B. L. Harvey, E. L. Cox, J. N. Rutger, G. Jelencovic, and E. Yagil. (U. California, Davis.) Identification of the ancestry of an amphiploid Viola with the aid of paper chromatography. Amer. Jour. Bot. 50 (8): 830–839. Illus. 1963.—Comparison of chromatograms obtained from extracts of dried leaves of various entities of the Viola purpurea complex as well as of V. pedunculata revealed the following. In respect to unidentified compounds differentially soluble in a mixture of tertiary butanol and acetic acid, with 15% acetic acid as a second solvent, the constitution of the tetraploid species V. quercetorum could be obtained by combining those of the diploid entities V. purpurea purpurea and V. aurea mohavensis. In respect to certain morphological characteristics, chiefly leaf shape and pubescence, beard hairs on lateral petals, anther appendages, and shape and hairs on styles and stigmas, V. quercetorum is intermediate between V. p. purpurea and V. a. mohavenis. The geographic distribution of V. quercetorum is likewise intermediate between those of the other 2 entities. Consequently, the origin of V. quercetorum by amphiploidy from hybrids between V. purpurea purpurea and V. aurea mohavensis is supported by 3 different lines of evidence. A possible place and time for this origin are the central Coast Ranges of California during the Pleistocene pluvial epoch. In both morphological characteristics and the chemical compounds revealed by the chromatograms, V. pedunculata subspp. pedunculata and tenuifolia show similarities and differences from members of the V. purpurea complex which are of a different nature than are the similarities and differences between the various entities of the latter complex. Consequently, the relationships between V. purpurea and V. pedunculata are probably not associated with or complicated by recent introgression or amphiploidy, and the 2 species may be rather distantly related to each other.
NATURAL HYBRIDS BETWEEN ORYZOPSIS AND STIPA. III. ORYZOPSIS HYMENOIDES × STIPA PINETORUM
Authors: Johnson B. Lennart
Published: January 2018

Johnson, B. Lennart. (U. California, Los Angeles.) Natural hybrids between Oryzopsis and Stipa. III. Oryzopsis hymenoides × Stipa pinetorum. Amer. Jour. Bot. 50(3): 228–234. Illus. 1963.—On the basis of morphological characters, the spontaneous hybrid Oryzopsis hymenoides × Stipa pinetorum is included in 0. bloomeri which consists of a number of sterile, natural hybrids between O. hymenoides (2n = 48) and various American species of Stipa (2n = 32‐82). While intermediate between its parents in many attributes, the pinetorum hybrid is different from the other hybrids included in O. bloomeri with respect to lemma‐hair length and other characters which are diagnostic for S. pinetorum (2n = 32). The hybrid has 2n = 40 chromosomes, but some plants of the hybrid and some of O. hymenoides had small supernumerary, somatic chromosomes. The parents formed only bivalents at meiosis. The hybrid showed some affinity among 14 chromosomes per sporocyte. This affinity is nearly as great as that shown by other Stiporyzopsis hybrids with 56 or 58 chromosomes, and is consistent with the earlier suggestion that bivalent formation in polyploid species of Stipa may be gene‐controlled.
TRIVALENT FORMATION IN MULTIPLE TRISOMICS OF CLARKIA UNGUICULATA
Authors: Vasek Frank C.
Published: January 2018

Vasek, F. C. (U. California, Riverside.) Trivalent formation in multiple trisomics of Clarkia unguiculata. Amer. Jour. Bot. 50(3): 244–247. 1963.—A series of multiple trisomics, ranging from 2n + 1 to 2m + 7, was scored for univalents and trivalents at first metaphase. The mean number of trivalents per cell per extra chromosome was 0.43, 0.46, 0.46, 0.56, 0.54, 0.55 and 0.59 for plants with 1, 2, 3, 4, 5, 6 and 7 extra chromosomes respectively. These trivalent frequencies are interpreted to fall into 2 classes, indicating that the cytological differences between triploids and single trisomies may be based on a threshold effect. The results are compared with available data from other genera, and it is suggested that the observed increase in trivalent formation per extra chromosome may be associated with an increase in chiasma frequency.
CALLIXYLON FROM THE UPPER DEVONIAN OF NORTHWESTERN ALBERTA
Authors: Campbell J. D.
Published: January 2018

Campbell, J. D. (Res. Council Alberta, Edmonton.) Callixylon from the Upper Devonian of northwestern Alberta. Amer. Jour. Bot. 50(7): 648–652. Illus. 1963.—An oil‐well core from the “Granite Wash” of probable early Late Devonian age (Wood bend equivalent) in the Peace River region of northwestern Alberta yielded a thin pyritized chip of coniferoid wood. The pith is not represented, but the secondary tracheid pitting, exhibiting radially aligned clusters of 5–10 araucarioid pits, indicates that the specimen is referable to the wood‐type usually called Callixylon, now believed to be the axis of the leaf‐genus Archaeopleris. In its low and regularly uniseriate or rarely biseriate rays, with no apparent ray tracheids, the specimen may resemble the species Callixylon trifdievi Zalessky (1909) from the Upper Devonian of Russia, and thus lend some small support to the postulation of a Late Devonian land connection between northwestern North America and Europe.
PHOTO‐INHIBITION OF SPORULATION IN ALTERNARIA SOLANI
Authors: LUKENS R. J.
Published: January 2018

Lukens, R. J. (Connecticut Agric. Expt. Sta., New Haven.) Photo‐inhibition of sporulation in Alternaria solani. Amer. Jour. Bot. 50(7): 720–724. Illus. 1963.—Day‐old conidiophores from starved cultures of Alternaria solani require a 12‐hr dark period to produce conidia. If the cultures are illuminated during the dark period, conidial production is inhibited. The action spectrum of light inhibiting conidial formation contains 2 maxima, a sharp one at 450 mμ and a broad one extending from 375 to 425 mμ. The entire action spectrum corresponds approximately to the absorption spectra of riboflavin‐5‐phosphate mononucleotide (FMN) and of 6‐carotene. FMN nullifies the effect of light in inhibiting sporulation, but b‐carotene does not. Flavins appear to be essential for conidial formation and are photo‐inactivated. It is likely that flavins are photo‐receptors through which light inhibits conidial formation in A. solani.
STEM ANATOMY AND ASPECTS OF DEVELOPMENT IN TOMATO
Authors: Thompson Neal P. , Heimsch Charles
Published: January 2018

Aspects of anatomical development were correlated with internodal growth in tomato plants, variety ‘Yellow Plum,’ grown for more than 3 months. Internodal length was measured weekly in control plants and those harvested for anatomical study. Gross structure indicated progressive development with increasing age. Primary xylem and phloem first mature in distinct strands and the strands are joined laterally by procambium to form a continuous vascular cylinder. Primary phloem occurs on the outer periphery of the procambium between the early‐formed vascular strands. Successive periclinal divisions in the procambium during internode elongation give rise to pronounced radial seriations of the cells. Procambial derivatives are included in the cylinder of thick‐walled, lignified vascular cells that become prominent after elongation ceases. Secondary xylem is of greater radial width in the stem sectors which include protoxylem. During early secondary growth, vessels develop in the secondary xylem only in these sectors. Nucleate fibers and rays constitute the remainder of the secondary xylem. The rays exhibit an organization noted in other plants of reduced growth habit. Some of these interpretations do not agree with those described for tomato in earlier studies, and they are discussed in relation to pertinent aspects of development.
THE ORIGIN, FERTILITY AND TRANSMISSION OF MONOSOMICS IN GOSSYPIUM
Authors: Brown Meta S. , Endrizzi J. E.
Published: January 2018

The origin of 51 monosomic plants in Gossypium hirsutum is described, and the great majority are shown to be fertile and transmissible. Both fertility and transmission rate can be increased by outcrossing and selection. Monosomics which have been isolated in a standard hirsutum background can be recognized by distinct morphological characteristics, including modifications of both vegetative and reproductive structures such as smaller or narrower leaves, smaller flowers or flower parts, and smaller, longer, or partially collapsed bolls. Monosomics involving the large chromosomes, i.e., the A genome, are recovered more frequently than are monosomics of the D (small chromosomes) genome. Furthermore, monosomics of certain of the A chromosomes are recovered more frequently than others. Of 20 identified hirsutum monosomics, 7 are chromosome A‐2, 7 are A‐4, 3 are A‐6, and 1 each is A‐1, D‐17 and D‐18.
A COMPARATIVE DEVELOPMENTAL STUDY OF THE MUTANT SIDESHOOTLESS AND NORMAL TOMATO PLANTS
Authors: Malayer Jeanette C. , Guard A. T.
Published: January 2018

'Sideshootless,’ a mutant strain of tomato which does not produce axillary buds during vegetative growth, was compared with normally branching plants in order to study the nature of development particularly with regard to axillary buds. Sectioned material revealed no indication of axillary bud initiation in the sideshootless plant at any time during the vegetative phase of growth. In the normal plants, buds were noted to arise in the axil of the fifth youngest leaf. The buds take their origin in tissue which is in direct continuity with the apical meristem. The bud primordia later become set apart from the apex as vacuolation takes place in the surrounding tissue. At the time of floral initiation, the mutant and normal strains behave similarly. Axillary buds appear in the axils of the 2 leaves immediately below the floral apex. One of the buds elongates to overtop the existing plant axis; the other develops as a typical sidebranch. The inflorescence is pushed aside in the process. This pattern is repeated with each inflorescence; thus an axis composed of several superimposed laterals results.
CYTOGENETIC STUDIES IN CLARKIA, SECTION PRIMIGENIA. II. A CYTOLOGICAL SURVEY OF CLARKIA ARCUATA AND CLARKIA LASSENENSIS
Authors: Snow Richard , Imam Amal
Published: January 2018

Clarkia arcuata and C. lassenensis are the 2 members of the subsection Flexicaules. Although closely related morphologically, they show very different patterns of chromosomal variability in nature. About 25% of the plants grown from wild seed of C. arcuata, a predominantly cross‐pollinating species, were heterozygous for 1 or 2 translocations; such heterozygotes were found in 5 of the 9 populations sampled. An analysis of the chromosome pairing in intraspecific crosses indicated that at least 5 different translocations giving a ring of 4 with the “standard” strain, 2 giving a ring of 6, and 2 giving a ring of 8 are present in nature. No arrangement was found with widespread distribution, and it is impossible to say at present what might be the primitive arrangement of this species. One population was found to contain an inversion, a rearrangement which is very rare in Clarkia at the intraspecific level. In C. lassenensis, a predominantly self‐pollinating species, only 6% (3 plants) of a sample of 53 were translocation heterozygotes, and these heterozygotes were found in only 2 of 13 populations. Intraspecific crosses indicated that one chromosome arrangement, the “standard,” was present throughout the species range.
BIOSYSTEMATIC STUDIES IN THE BOUTELOUA CURTIPENDULA COMPLEX. III. POLLEN SIZE AS RELATED TO CHROMOSOME NUMBERS
Authors: Kapadia Z. J. , Gould F. W.
Published: January 2018

Pollen size statistics are presented for 10 closely related species of Bouteloua and relationships between pollen size and chromosome numbers are presented for 13 populations of 5 species and 3 varieties. With 1 exception, all populations of all taxa conformed to a general pattern of pollen size dependent upon chromosome number. Chromosome numbers varied from 2n = 20 to 2n = ca. 103, with several independent aneuploid series. Statistical analyses were made of pollen size as related to chromosome number in the 3 varieties of B. curtipendula. These data showed that tetraploids (2n = 40) of var. tenuis had significantly greater pollen size and coefficient of variation than diploids (2n = 20) of the same variety. Similarly, aneuploids of var. curtipendula with 2n = 45 to 2n = 64 chromosomes had significantly larger and more variable pollen than tetraploids (2n = 40) of the same variety. Highly significant positive regression coefficients were obtained from analyses of chromosome numbers and mean pollen size, and chromosome numbers and coefficient of variation, for var. curtipendula. Regression coefficients for var. caespitosa populations with chromosome numbers over the hexaploid (2n = 60) level were not significant.
MORPHOLOGY OF HYPOMYCES TRICHOTHECOIDES
Authors: Hanlin Richard T.
Published: January 2018

Large, spirally coiled initials embedded in a subiculum develop into multicellular, multinucleate ascogonia. Hyphae grow up around them to form a prosenchymatous perithecial wall. The ascogonia give rise to multinucleate ascogenous cells from which croziers and asci form. As the ascocarp develops, an apical meristem produces uninucleate cells that elongate downward into long, slender filaments, the apical paraphyses. From a basal layer of ascogenous cells, asci grow up among the apical paraphyses, which disintegrate as the ascocarp matures. Ascospores are verrucose, with obtuse apiculi. This pattern of development is typical of the Nectria‐type of Luttrell.
THE BREEDING SYSTEM OF OXALIS SUKSDORFII
Authors: Ornduff Robert
Published: January 2018

The Pacific Coast species Oxalis suksdorfii (section Corniculatae) is morphologically tristylous. Flowers of the 3 kinds of plants present in natural populations differ in style length, stamen length, pollen size, stigma size and orientation, and stylar pubescence. Experimental studies and field observations indicate that plants with long‐styled flowers are weakly self‐compatible and show little differentiation in size or compatibility relationships of pollen from the 2 sets of stamens. Plants with mid‐styled flowers have strongly differentiated pollen, but produce few capsules or seed after any artificial or natural pollinations. Plants with short‐styled flowers are self‐incompatible and show slight pollen differentiation. The data presented suggest that O. suksdorfii approaches functional dimorphism since the mid‐styled form contributes little pollen and few seeds in sexual reproduction. The species may be in the process of losing the mid‐styled form completely and provides a model of certain physiological and morphological changes which may have accompanied elimination of the mid‐styled form in other Oxalis species. The abundance of plants with mid‐styled flowers in natural populations suggests, however, that this form may be retained because it contributes to general population fitness, or because the genetic control of heterostyly in this species prevents its elimination.
A CYTOCHEMICAL STUDY OF EMBRYO SAC DEVELOPMENT IN STELLARIA MEDIA
Authors: Pritchard Hayden N.
Published: January 2018

Megasporogenesis and embryo sac development in Stellaria media were investigated using cytochemical methods for the demonstration of nucleic acids, proteins, and polysaccharides. RNA concentrations were high in the archesporial cells, low in the megaspore mother cell, and increased again to high concentrations with the formation of the megaspore and 2‐, 4‐, and early 8‐nucleate embryo sac. RNA levels were also high in the egg and primary endosperm nucleus but low in the synergid and antipodal cells. Nucleolar size and vacuolation were indicative of RNA synthetic activity. Protein concentrations were parallel in concentration and distribution to those observed for RNA. Polysaccharides were conspicuously absent from all stages except the synergids and nucellar cells. Feulgen‐stained DNA was demonstrable in the antipodal cells, megaspore mother cell, and megaspore cell, but was not visible in the 2‐, 4‐, or early 8‐nucleate embryo sac. Feulgen staining was also absent from the egg and primary endosperm nucleus but was visible in the synergids and antipodals. Histones were difficult to visualize anywhere except in the egg cytoplasm and the nuclei of the antipodals.