The advantage of long-distance clonal spreading in highly disturbed habitats

1994 ◽  
Vol 8 (2) ◽  
pp. 172-187 ◽  
Author(s):  
Lenore Fahrig ◽  
Debra P. Coffin ◽  
William K. Lauenroth ◽  
Herman H. Shugart
Keyword(s):  
Long Distance ◽  
Disturbed Habitats

Survival strategies of Silene tatarica (Caryophyllaceae) in riparian and ruderal habitats

2004 ◽  
Vol 82 (4) ◽  
pp. 491-502 ◽  
Author(s):  
Anne Jäkäläniemi ◽  
Anneli Kauppi ◽  
Antti Pramila ◽  
Kalle Vähätaini
Keyword(s):  
Ground Surface ◽  
Survival Strategies ◽  
Long Distance ◽  
Anatomical Structures ◽  
Riparian Plants ◽  
Vascular Elements ◽  
Flat Shape ◽  
Habitat Properties ◽  
Silene Tatarica ◽  
Disturbed Habitats

Certain morphological and anatomical structures of riparian plants might be important for their survival during the season when they are exposed to severe stress caused by flooding, burial, fluctuating temperatures, and drought. These rare characteristics were studied as related to their ecological consequences in a threatened plant, Silene tatarica (L.) Pers., in riparian and ruderal habitats. The main differences between the habitats were morphological and closely related to the habitat properties, whereas the basic anatomy of structures was similar. After sand burial, most riparian plants formed vertical rhizomes and new meristems by bud ramification in the stem base near the ground surface. Special anatomical structures of fleshy underground stems and roots seem to allow plants to be resilient. Moreover, some primitive structures, such as vascular elements with helical and scalariform thickenings, collenchyma, and abundant xylem parenchyma, may increase the resilience of organs. High amounts of saccharose in fleshy rhizomes and roots can increase the cold resistance of plants. The flat shape and structures of tiny seeds may enhance the long-distance dispersal by water. We suggest that the synergism of these structures enables the survival of S. tatarica in highly disturbed habitats with fluctuating water levels.Key words: bud clusters, burial, flooding, growth habit, tensile strength, vertical rhizome.

Color, brightness, and other floral characteristics attracting insects to the blossoms of some Canadian weeds

1973 ◽  
Vol 51 (10) ◽  
pp. 1939-1952 ◽  
Author(s):  
Gerald A. Mulligan ◽  
Peter G. Kevan
Keyword(s):  
Breeding Systems ◽  
Central Portion ◽  
Long Distance ◽  
Outer Portion ◽  
Large Populations ◽  
Pollen Vectors ◽  
Pollinating Insects ◽  
Disturbed Habitats

This paper is concerned with those floral characteristics that appear most important in the long-distance attraction of pollinating insects to the blossoms of weeds: color and brightness of flowers, size of the flower target, and the odor of the flowers. Weed flowers that are occasionally or frequently visited by insects tend to have a higher reflectance in ultraviolet and in blue than do flowers that are rarely visited. The flowers most visited, generally have flower targets over 20 mm in diameter and (or) flowers that are odoriferous. None of these characteristics appears to be of prime importance in determining which kinds of insects visit the flowers of weeds. Many weeds have flowers or flower heads with the outer portion reflecting ultraviolet and (or) blue wavelengths and a central portion absorbing these wavelengths. These flower characteristics, and information on life durations, breeding systems, and pollen vectors are used to evaluate the different strategies that enable weeds to rapidly build up large populations in constantly disturbed habitats.

The Fine Structure of Phloem Cells

1985 ◽  
Vol 43 ◽  
pp. 632-635
Author(s):  
James Cronshaw
Keyword(s):  
Structural Studies ◽  
High Concentration ◽  
Long Distance ◽  
Phloem Tissue ◽  
Sieve Elements ◽  
Long Distance Transport ◽  
P Protein ◽  
Companion Cells ◽  
Electron Microscopical ◽  
Distance Transport

Long distance transport in plants takes place in phloem tissue which has characteristic cells, the sieve elements. At maturity these cells have sieve areas in their end walls with specialized perforations. They are associated with companion cells, parenchyma cells, and in some species, with transfer cells. The protoplast of the functioning sieve element contains a high concentration of sugar, and consequently a high hydrostatic pressure, which makes it extremely difficult to fix mature sieve elements for electron microscopical observation without the formation of surge artifacts. Despite many structural studies which have attempted to prevent surge artifacts, several features of mature sieve elements, such as the distribution of P-protein and the nature of the contents of the sieve area pores, remain controversial.

Popliteal entrapment syndrome and age

VASA ◽  
2012 ◽  
Vol 41 (4) ◽  
pp. 262-268 ◽  
Author(s):  
Schweizer ◽  
Hügli ◽  
Koella ◽  
Jeanneret
Keyword(s):  
Risk Factors ◽  
Leg Pain ◽  
Walking Distance ◽  
Therapeutic Approaches ◽  
Long Distance ◽  
Entrapment Syndrome ◽  
Long Distance Running ◽  
Popliteal Entrapment ◽  
Popliteal Entrapment Syndrome ◽  
Atherosclerotic Risk Factors

On the occasion of diagnosing a popliteal entrapment syndrome in a 59-year old man with no cardiovascular risk factors, who developed acute ischemic leg pain during long distance running, we give an overview on this entity with emphasis on patients’age. The different types of the popliteal artery compression syndrome are summarized. The diagnostic and therapeutic approaches are discussed. The most important clinical sign of a popliteal entrapment syndrome is the lack of atherosclerotic risk factors in patients with limited walking distance. Not only in young athletes but also in patients more than 50 years old the popliteal entrapment syndrome has to be taken into account.

Attachment Styles, Physical Proximity, and Relational Satisfaction

2014 ◽  
Vol 4 (2) ◽  
pp. 106-112
Author(s):  
Anita Shrivastava ◽  
Andrea Burianova
Keyword(s):  
Attachment Styles ◽  
Romantic Relationship ◽  
Distinct Type ◽  
Relational Satisfaction ◽  
Long Distance ◽  
Avoidant Attachment ◽  
Geographic Separation ◽  
Relationship Of ◽  
Attachment Dimensions

This study aimed to explore the relationships between attachment styles, proximity, and relational satisfaction. This was achieved by assessing a distinct type of long distance romantic relationship of flying crews, compared with proximal (non-flying crew) romantic relationships. The responses of 139 expatriate professionals revealed significant associations between proximity and anxious and avoidant attachment dimensions. The role of the avoidant dimension in comparison with that of the anxious dimension was found to be a significant predictor of relational satisfaction. This study contributes significantly toward addressing the role of proximity and attachment in relational satisfaction in a new context of geographic separation.

Long-distance plant traffic

Nature ◽  
2001 ◽  
Author(s):  
Helen Pearson
Keyword(s):  
Long Distance
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