Plants, vascular

The word lignin is derived from the Latin word lignum meaning wood. It is a main component of vascular plants. Indeed, lignin is second only to polysaccharides in natural abundance, contributing 24—33% and 19—28%, respectively, to dry wood weights of normal softwoods and temperate-2one hardwoods. 

Silurian 440 Myr Sea levels rise, two large continents form, hothouse climate. Diversification of jawless fishes, first bony fishes invasion of land by vascular plants and arthropods... 

Carboniferous 345 Myr Climate cools, marked latitudinal gradients. Extensive forests of early vascular plants, especially club mosses, horsetails, ferns. Coal beds form. Amphibians diversify first reptiles appear. Radiation of early insect orders... 

Mosses and liverworts (Bryophyta) are more complex than algae. Some of the larger species have structures that superficially appear similar to roots, stems and leaves, but they lack the internal conducting systems present in the vascular plants (Tracheophyta). Internal transport systems (vascular systems) make possible the large sizes of terrestrial plants where the soil is the source of some requisites (water, mineral nutrients) and the air is the source of others (CO2, sunlight). The different groups of vascular plants are characterized primarily by their methods of reproduction. Vascular plants are the source of all wood. 

The consequences of the massive "loss" of energy accompanying passage from one trophic level to another also include the fact that organisms low in the trophic ladder tend to dominate the cycling of elements through the biosphere. This is especially true on land where vascular plants dominate both the physical structure and... 

Bjorkman, O. Demmig, B. (1987). Photon yield of oxygen evolution and chlorophyll fluorescence characteristics at 77 K among vascular plants of diverse origins. Planta, 170, 489-504. 

Among resurrection plants two seemingly very different kinds of response occur at the ultrastructural level. In many desiccation tolerant seeds, pollens, mosses and vascular plants, dehydration brings about rather... 

Gaff, D.F. (1977). Desiccation tolerant vascular plants of southern Africa. Oecolo-gia, 31, 95-109. 

Lewis, D.H. (1984). Occurrence and distribution of storage carbohydrates in vascular plants. In Storage Carbohydrates in Vascular Plants, ed. D.H. Lewis, pp. 1-32. Cambridge Cambridge University Press. 

Storage carbohydrates in vascular plants. Edited by D.H. Lewis... 

Miller (1989) is the question of how such an ancient organism has come to exist on a comparatively new oceanic island. Long-distance dispersal is an unlikely explanation for the present situation. Dispersal over shorter distances from island to island seems a reasonable possibility, with subsequent disappearance of many, or apparently all in the present case, of the intermediate stepping stones. Invocation of island hopping, after all, has many precedents. As Miller (1989) pointed out, obviously some vascular plant lineages have survived, some of which may have histories that reach back to the Antarctic flora. Needless to say, deep phylogenetic analyses would be helpful in addressing this question. 

Hitchcock, C. L., Cronquist, A., Ownbey, M., and Thompson, J. W. 1969. Vascular Plants of the Pacific Northwest. Part I. Vascular Cryptograms, Gymnosperms, and Monocotyledons. University of Washington Press, Seattle, WA. 

Porter, D. M. 1983. Vascular plants of the Galapagos Origins and dispersal. Pages 33-96 in... 

The whole process of chlorophyll disappearance in vascular plants is a complex multistep pathway, much as chlorophyll biosynthesis is, but for didactic reasons it can be abbreviated into two main stages. The first group of reactions produces greenish derivatives while the more advanced steps produce colorless compounds by an oxidative ring opening, analog to the oxygenolytic rupmre of the porphynoid macrocycle of haem. It is a very rapid process and despite considerable efforts, the detection of intermediates is difficult. ... 

Lunney AA, BA Zeeb, KJ Reimer (2004) Uptake of weathered DDT in vascular plants potential for phytoremediation. Environ Sci Technol 38 6147-6154. 

The flavonoids universally occur in vascular plants, in which they are often responsible for the colors of flowers and fruits, although they are also present (often less apparently) in roots, stems, and leaves [10]. The number of possible sources from which these compoimds can be isolated is very large and much useful information on this can be obtained in reviews [10-12]. 

Non-vascular plants Bryophyta Ulva and Chlamydomona Mosses, liverworts, hornworts 24,000... 

Vascular plants a) Seedless plants Ferns, horsetails, club mosses 13,000... 

Many secondary phenolic compounds are derived from the amino acids phenylalanine and tyrosine and therefore contain an aromatic ring and a three-carbon side chain (see Fig. 3.3). Phenylalanine is the primary substrate for phenylpropanoid synthesis in most higher vascular plants, with tyrosine being used to a lesser extent in some plants. Because of their common structure, compounds derived from these amino acids are collectively called phenylpropanoids. 

Condensation of coumaric acid with malonic acid yields the basic chalcone and stilbane skeletons (see Fig. 3.6). Stilbenes are found in most vascular plants, where they exhibit fungicidal and to a lesser extent antibiotic properties. They function as both constitutive and inducible defense substances. Some stilbenes inhibit fungal spore germination and hyphal growth, whereas others are toxic to insects and parasitic nematodes (round-worms). They also possess antifeeding and nematicide properties in mammals. For example, resveratrol (a stilbene in red wine) suppresses tumor formation in mammals. 

Alkaloids are compounds that contain nitrogen in a heterocyclic ring and are commonly found in about 15-20% of all vascular plants. Alkaloids are subclassified on the basis of the chemical type of their nitrogen-containing ring. They are formed as secondary metabolites from amino acids and usually present a bitter taste accompanied by toxicity that should help to repel insects and herbivores. Alkaloids are found in seeds, leaves, and roots of plants such as coffee beans, guarana seeds, cocoa beans, mate tea leaves, peppermint leaves, coca leaves, and many other plant sources. The most common alkaloids are caffeine, theophylline, nicotine, codeine, and indole... 

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