Plant spores

Airborne material affecting the quality of indoor air may be classified as gases or particulate matter. Gases which may be potential problems are radon, CO, NOj, and hydrocarbons. Particulate matter may come from tobacco smoke, mold spores, animal dander, plant spores, and others as shown in Table 23-1. Other factors interact to influence our perception of indoor air quality, including humidity, temperature, lighting, and sound level. 

Secondary Hazards Mechanical vectors (planting) Spores Crop debris. 

The physical or petrographic components of coal are defined or described in various ways. In one system, which depends on microscopic observation, the principal components are called exinite, vitrinite, micrinite, and fusinite. Transparency of these in a thin section decreases in that order, whereas reflectance from polished surface increases in the same order. Vitrinite, the major component of most coals, occurs in bands or strands and is usually uniform in appearance, though sometimes shows cell structure exinite consists of the remains of plant spores, pollen, and cuticles with characteristic shape micrinite occurs in very fine granular form or massive structureless, irregular form fusinite shows characteristic fibrous, cellular structure. Semifusinite is transitional between vitrinite and fusinite. On a macroscopic scale, vitrain and... 

Palynology is the study of fossil pollen (and sometimes plant spores) extracted from lake sediment, peat bog, or other matrices. The most common goal of paly-nological research is to reconstruct the probable character of historical plant communities, inferred from the abundance of species in dated portions of the fossil pollen record. Pollen analysis is an extremely useful tool for understanding the character of ancient vegetation and its response to changes in environmental conditions, particularly in climate. Pollen analysis also has an economically important modem industrial use in the exploration for resources of fossil fnels. Palynology is also used to help reconstmct the probable habitats and foods of ancient humans and of wild animals. 

The toxins also keep plant spores or animal larvae from growing on their surfaces. 

Gray, J. (1988) Land plant spores and the Ordovician-Silurian boundary. Bulletin of the British Museum (Natural History) Geology, 43, 351-358. 

On the macroscopic scale, two coal classifications have been used humic or banded coals and sapropeflc or nonbanded coals. Stratification in the banded coals, which result from plant parts, is quite obvious the nonbanded coals, which derive from algal materials and spores, are much more uniform. The physical and chemical properties of the different layers in a piece of coal or a seam can vary significantly. Therefore the relative amounts of the layers are important in determining the overall characteristics of the mined product. Coal petrography has been widely appHed in cokemaking and is important in coal hquefaction programs. 

Macerals. Coal parts derived from different plant parts, are referred to as macerals (13). The maceral names end in "-inite" as do the mineral forms of rocks. The most abundant (about 85%) maceral in U.S. coal is vitrinite, derived from the woody tissues of plants. Another maceral, called liptinite, is derived from the waxy parts of spores and poUen, or algal remains. The liptinite macerals fluoresce under blue light permitting a subdivision based on fluorescence. A third maceral, inertinite, is thought to be derived from oxidized material or fossilized charcoal remnants of early forest fires. 

In addition to the mechanisms of stress response so far considered, there are several others which have attracted the attention of plant ecologists. These include innate or environmentally determined forms of dormancy in seeds, spores, and vegetative buds, many of which represent adaptive responses restricting plant growth and development to favourable seasons or sites. Dormancy has been the subject of numerous publications and will not be considered here. Instead, opportunity will be taken to refer to two forms of plant response to stress which until recently have received only scarce attention. The first is the phenomenon of stored growth whilst the second involves the response of the developing shoot to mechanical impedance. 

There are representatives of desiccation tolerant species amongst all of the major plant divisions. The water content of many bacterial and fungal spores is low (<25%) and they exhibit great tolerance of desiccation (see Ross Billing, 1957 Bradbury et ai, 1981). Desiccation tolerant cyanobacteria are found in a diverse range of drought-prone habitats. 

---