DEVELOPMENT OF THE SEED CONE OF DOUGLAS-FIR FOLLOWING DORMANCY

1965 ◽  
Vol 43 (2) ◽  
pp. 317-332 ◽  
Author(s):  
John N. Owens ◽  
Frank H. Smith
Keyword(s):  
Early Development ◽  
Maximum Size ◽  
Developmental Cycle ◽  
Surface Layers ◽  
Adaxial Surface ◽  
Single Leaf ◽  
Separate Branch ◽  
Cycle Growth ◽  
Seed Cone ◽  
Lateral Shoots

Development of the megasporangiate cone during the period of enlargement and maturation following dormancy is described in detail. This work, in conjunction with the early development previously described, provides a complete description of the 17 month developmental cycle. Growth of the megasporangiate cone is resumed in early March near Corvallis, Oregon, and the cone buds burst about 1 month later. The cone elongates rapidly by intercalary growth. Bracts enlarge but the shape of the bract established prior to dormancy is essentially maintained. The scale assumes a spoon-shaped appearance as a result of a form of marginal growth. Vascularization, and development of other tissues within the bract and scale, indicates that bracts are homologous to leaves and basically similar in structure, but scales are highly modified fertile lateral shoots. Each bract is supplied by a single leaf trace and each scale by two separate branch traces. The seed wings differentiate from adaxial surface layers of each scale. A large zone of macrosclereids differentiates in the basal abaxial portion of the scale. The cone reaches its maximum size early in July and maturation of tissues occurs in July and August, and is generally complete early in September. Cone opening results from drying and shrinkage of the macrosclereids at the base of the scale.

THE INITIATION AND EARLY DEVELOPMENT OF THE SEED CONE OF DOUGLAS FIR

1964 ◽  
Vol 42 (8) ◽  
pp. 1031-1047 ◽  
Author(s):  
John N. Owens ◽  
Frank H. Smith
Keyword(s):  
Early Development ◽  
Subsequent Development ◽  
Peripheral Zone ◽  
Leaf Axil ◽  
Cortical Cells ◽  
Lateral Buds ◽  
Seed Cone ◽  
Lateral Shoots ◽  
Similar Growth ◽  
Growth Periodicity

The initiation and early development of lateral vegetative, megasporangiate, and microsporangiate buds is described. The subsequent development of the megasporangiate cone prior to dormancy is described in detail. Initiation of lateral buds from cortical cells above the leaf axil occurs early in April and is similar in the three bud types. Apical zonation becomes apparent by mid-May but is less distinct in the microsporangiate primordium because of its smaller size. The microsporangiate bud remains distinctly smaller until microsporophyll initiation. Apical enlargement occurs in mid-July, at the end of the period of cataphyll initiation, and marks the onset of subsequent foliar initiation (leaves, bracts, and microsporophylls). Like the cataphylls, these foliar organs are presaged by procambial differentiation from the peripheral zone outward to the base of the presumptive primordium. No distinct apical initials appear in any of the foliar organs. A group of subapical initials is active during early development but they soon differentiate and further elongation occurs by intercalary growth. Bract initiation ends early in October. The apices of the three bud types show a similar growth periodicity and become greatly reduced in size and distinctness of zonation during foliar initiation. Scale initiation in the megasporangiate bud begins early in September and continues until the cones become dormant early in November. Scales are initiated from axillary cells at the base of the bracts. Apical zonation similar to other lateral shoots is present during early development but the organization changes to a type of submarginal growth.

Fruit Set in Lupinus angustifolius Cv. Unicrop. II. Assimilate Flow During Flowering and Early Fruiting

1981 ◽  
Vol 8 (3) ◽  
pp. 307 ◽  
Author(s):  
JS Pate ◽  
P Farrington
Keyword(s):  
Lupinus Angustifolius ◽  
Main Stem ◽  
Carbon Dioxide Exchange ◽  
Sink Strength ◽  
Plant Parts ◽  
Single Leaf ◽  
Lateral Shoots ◽  
Using Data ◽  
A Minor ◽  
Stem Leaf

Assimilate distribution in Lupinus angustifolius was studied during 7 weeks after emergence of the main inflorescence by feeding [14C]urea to a single leaf or group of leaves on a plant and measuring 14C in plant parts 24 h after feeding. Nine times of feeding were involved, each with 14C treatments encompassing leaves of the main stem and first-order laterals. The inflorescence was a minor sink for assimilates compared with root, main stem and developing lateral shoots. During the first 4 weeks the inflorescence relied on main stem leaves, especially the upper leaves, but in the fifth week leaves of upper laterals became principal sources of assimilates. The transition occurred after four to six basal fruits had set, and just as upper flowers were commencing to abscise. Estimates were made of transfer of photosynthetically fixed carbon from the uppermost main stem leaf to the inflorescence, using data on carbon dioxide exchange and changes in carbon content of this leaf and its translocatory commitment to the inflorescence as determined by 14C feeding. Assimilate flow from leaves to flowers was confined largely to organs of the same or adjacent orthostichies (2/5 phyllotaxis), but these affinities became less definite during fruiting. Import of 14C by reproductive units was related to phenology, position on an inflorescence, and accumulation of dry matter. All flowers attracted assimilates strongly at the bud stage but lost sink strength progressively after opening. Upper flowers destined to abscise failed to import assimilates or to bleed from phloem for several days before being shed. Lower flowers which set fruits showed a rapid resurgence of sink strength once their corollas had senesced and the young fruits had commenced to elongate.

Bud development in Sitka spruce. II. Cone differentiation and early development

1976 ◽  
Vol 54 (8) ◽  
pp. 766-779 ◽  
Author(s):  
John N. Owens ◽  
Marje Molder
Keyword(s):  
Phenolic Compounds ◽  
Early Development ◽  
Shoot Elongation ◽  
Picea Sitchensis ◽  
Lateral Shoot ◽  
Bud Development ◽  
Seed Cone ◽  
Mitotic Frequency ◽  
Mother Cells ◽  
Pollen Cone

Pollen-cone and seed-cone buds of Picea sitchensis (Bong.) Carr. are found as either terminal or axillary buds. Pollen cones are most likely to develop from small axillary apices on vigorous distal shoots or small terminal apices on less vigorous, proximal shoots. Seed cones are most likely to develop from large, distal axillary apices on vigorous shoots or smaller terminal apices on less vigorous shoots. All apices became mitotically active late in March, passed through a 3.5-month period of bud-scale initiation, and in mid-July became differentiated as vegetative, pollen-cone, or seed-cone apices. Potentially pollen-cone apices were smaller, had a lower mitotic frequency during bud-scale initiation, and produced fewer bud scales than apices which developed into seed-cone or vegetative buds. During bud-scale initiation all apices had a few strands of cells containing phenolic compounds in the developing pith. At the time of bud differentiation, the pith of vegetative apices accumulated more phenolic compounds and non-phenolic ergastic materials, whereas the pith of reproductive apices did not. This was followed by a marked increase in mitotic frequency in reproductive apices, resulting in changes in apical size and shape. Leaf, bract, and microsporophyll initiation began about the end of July. All microsporophylls were initiated by the end of August. Sporogenous cells developed, but meiosis did not occur before the pollen cones became dormant at the end of October. Two-thirds of the bracts were initiated by the end of August. The remaining bracts were initiated more slowly until dormancy. Ovuliferous scales were initiated for 3 months beginning in September, and megaspore mother cells appeared but did not undergo meiosis before seed cones became dormant at the end of November. There was no difference in the time of vegetative, pollen-cone, and seed-cone bud differentiation, which occurred at the end of lateral shoot elongation.

New fossil Pinaceae from the Early Cretaceous of Mongolia

Botany ◽  
2016 ◽  
Vol 94 (9) ◽  
pp. 885-915 ◽  
Author(s):  
Fabiany Herrera ◽  
Andrew B. Leslie ◽  
Gongle Shi ◽  
Patrick Knopf ◽  
Niiden Ichinnorov ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Early Cretaceous ◽  
Distal Portion ◽  
Adaxial Surface ◽  
Anatomical Features ◽  
Central Mongolia ◽  
Seed Cone

Exceptionally well-preserved pinaceous leaves and seed cones are abundant in unconsolidated Early Cretaceous lignites in central Mongolia. These fossils include two seed cones, both of which have helically arranged bract–scale complexes with two winged seeds on the adaxial surface. The larger of the two seed cones, described as Picea farjonii sp. nov., is cylindrical to ellipsoidal, and was borne terminally on a stout shoot. The bract is small and tridentate. Leaf bases on the shoots are helically arranged, and attached leaves are linear and flattened. In all of the morphological and anatomical features that are preserved, P. farjonii is very similar to extant Picea. The smaller seed cone, described as Pityostrobus stockeyae sp. nov., shows features of several genera of extant Pinaceae. This cone is ellipsoidal and was borne terminally on a long, slender shoot. The bract is thin and triangular proximally, but the distal portion is thicker, needle-like, and deciduous. Picea farjonii and Pityostrobus stockeyae were abundant in conifer-dominated swamps in Mongolia during the Aptian–Albian and provide further support for the importance of plants related to extant Pinaceae in the vegetation of the Northern Hemisphere at this time.

Stockeystrobusgen. nov. (Cupressaceae), and the evolutionary diversification of sequoioid conifer seed cones

Botany ◽  
2016 ◽  
Vol 94 (9) ◽  
pp. 847-861 ◽  
Author(s):  
Gar W. Rothwell ◽  
Tamiko Ohana
Keyword(s):  
Reproductive Biology ◽  
Late Cretaceous ◽  
Japanese Island ◽  
Single Row ◽  
Adaxial Surface ◽  
Evolutionary Diversification ◽  
Seed Cone ◽  
Conifer Seed ◽  
Major Plane ◽  
Living Species

An anatomically preserved seed cone from Late Cretaceous (Santonian–Coniacian) sediments of the Yezo Group on the Japanese Island of Hokkaido documents additional diversity among sequoioid conifers, and reveals previously unknown mechanisms for pollination and post-pollination seed enclosure in the conifer family Cupressaceae. The cylindrical seed cone of Stockeystrobus interdigitata gen. et sp. nov., consists of a central axis bearing helically arranged bract–scale complexes. Individual complexes are tightly packed and peltate in form, with completely fused bracts and scales. Peltate heads of adjacent complexes are attached to each other by elongated interdigitating epidermal trichomes. Each complex bears 6–8 inverted seeds on the adaxial surface of the inside of the peltate bract–scale complex head. Seeds occur in a single row, are roughly disk shaped, with broad wings in the major plane of symmetry. The nucellus is attached to the seed integument at the chalaza and free distally, with a convoluted apex. This cone reveals greater diversity of sequoioid reproductive biology than is represented among living species, and demonstrates that completely enclosed cones with well protected seeds were produced by Late Cretaceous fossil conifers of the Cupressaceae.

Individual differences, social attention, and the history of the social motivation hypotheses of autism

2019 ◽  
Vol 42 ◽  
Author(s):  
Peter C. Mundy
Keyword(s):  
Individual Differences ◽  
Early Development ◽  
Emotional Development ◽  
Social Motivation ◽  
Social Attention ◽  
Social Emotional Development ◽  
Social Emotional ◽  
Precise Understanding ◽  
The Social ◽  
History Of

Abstract The stereotype of people with autism as unresponsive or uninterested in other people was prominent in the 1980s. However, this view of autism has steadily given way to recognition of important individual differences in the social-emotional development of affected people and a more precise understanding of the possible role social motivation has in their early development.

Classical social reward signatures in infants with later ASD

2019 ◽  
Vol 42 ◽  
Author(s):  
Teodora Gliga ◽  
Mayada Elsabbagh
Keyword(s):  
Early Development ◽  
Social Motivation ◽  
Self Report ◽  
Social Reward ◽  
Socially Motivated

Abstract Autistic individuals can be socially motivated. We disagree with the idea that self-report is sufficient to understand their social drive. Instead, we underscore evidence for typical non-verbal signatures of social reward during the early development of autistic individuals. Instead of focusing on whether or not social motivation is typical, research should investigate the factors that modulate social drives.

Comments on collision mechanics in ring systems

1984 ◽  
Vol 75 ◽  
pp. 407-422
Author(s):  
William K. Hartmann
Keyword(s):  
Asteroid Belt ◽  
Surface Erosion ◽  
Surface Layers ◽  
Ring Systems ◽  
Eclipse Observations ◽  
Saturn’S Rings ◽  
Saturn's Rings

ABSTRACTThe nature of collisions within ring systems is reviewed with emphasis on Saturn's rings. The particles may have coherent icy cores and less coherent granular or frosty surface layers, consistent with thermal eclipse observations. Present-day collisions of such ring particles do not cause catastrophic fragmentation of the particles, although some minor surface erosion and reaccretion is possible. Evolution by collisional fragmentation is thus not as important as in the asteroid belt.

Early Development of Drug-Induced Hepatic Necrosis

1971 ◽  
Vol 29 ◽  
pp. 576-577
Author(s):  
F. G. Zaki ◽  
E. Detzi ◽  
C. H. Keysser
Keyword(s):  
Early Development ◽  
Hepatic Necrosis ◽  
Screening Tests ◽  
Dense Matrix ◽  
Sprague Dawley ◽  
Electron Microscopic ◽  
Drug Induced ◽  
Hepatocellular Damage ◽  
Sprague Dawley Rats ◽  
Microscopic Studies

This study represents the first in a series of investigations carried out to elucidate the mechanism(s) of early hepatocellular damage induced by drugs and other related compounds. During screening tests of CNS-active compounds in rats, it has been found that daily oral administration of one of these compounds at a dose level of 40 mg. per kg. of body weight induced diffuse massive hepatic necrosis within 7 weeks in Charles River Sprague Dawley rats of both sexes. Partial hepatectomy enhanced the development of this peculiar type of necrosis (3 weeks instead of 7) while treatment with phenobarbital prior to the administration of the drug delayed the appearance of necrosis but did not reduce its severity.Electron microscopic studies revealed that early development of this liver injury (2 days after the administration of the drug) appeared in the form of small dark osmiophilic vesicles located around the bile canaliculi of all hepatocytes (Fig. 1). These structures differed from the regular microbodies or the pericanalicular multivesicular bodies. They first appeared regularly rounded with electron dense matrix bound with a single membrane. After one week on the drug, these vesicles appeared vacuolated and resembled autophagosomes which soon developed whorls of concentric lamellae or cisterns characteristic of lysosomes (Fig. 2). These lysosomes were found, later on, scattered all over the hepatocytes.

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