Trapped In Time - Chapter 124

Flowers of Poaceae are characteristically arranged in spikelets, each having one or more florets. The spikelets are further grouped into panicles or spikes. The part of the spikelet that bears the florets is called the rachilla. A spikelet consists of two (or sometimes fewer) bracts at the base, called glumes, followed by one or more florets. A floret consists of the flower surrounded by two bracts, one external—the lemma—and one internal—the palea. The flowers are usually hermaphroditic—maize being an important exception—and mainly wind-pollinated, although insects occasionally play a role. The perianth is reduced to two scales, called lodicules, that expand and contract to spread the lemma and palea; these are generally interpreted to be modified sepals. This complex structure can be seen in wheat (Triticum aestivum) spikelet. The fruit of grasses is a caryopsis, in which the seed coat is fused to the fruit wall. A tiller is a leafy shoot other than the first shoot produced from the seed.

Grass blades grow at the base of the blade and not from elongated stem tips. This low growth point evolved in response to grazing animals and allows grasses to be grazed or mown regularly without severe damage to the plant.

The success of the grasses lies in part in their morphology and growth processes and in part in their physiological diversity. Most of the grasses divide into two physiological groups, using the C3 and C4 photosynthetic pathways for carbon fixation.

The C4 grasses are “warm season” grasses. These have a photosynthetic pathway, linked to specialized Kranz leaf anatomy, which allows for increased water use efficiency, rendering them better adapted to hot, arid environments and those lacking in carbon dioxide.

The C3 grasses are referred to as “cool-season” grasses.

Annual cool-season – wheat, rye, annual bluegrass (annual meadowgrass, Poa annua), and oat.

Perennial cool-season – orchardgrass (cocksfoot, Dactylis glomerata), fescue (Festuca spp.), Kentucky bluegrass and perennial ryegrass (Lolium perenne).

Annual warm-season – maize, sudangrass, and pearl millet

Perennial warm-season – big bluestem, Indiangrass, Bermudagrass and switchgrass.

Shena was fascinated with the information being provided and said that she never knew that the cereals we ate were also from the grasses.

To a question from Chris about further information, the grass replied that the entire information was already in the World Wide Web or Internet as we call it.

The grass also added that there was more information and it had just given us an overview. It had not been programmed to go into full details.

It requested us to be patient and that it would answer any questions as long as they were included in its program. It then started to give some more information.

Grasses are unusual in that the meristem is located near the bottom of the plant; hence, they can quickly recover from cropping at the top. The evolution of large grazing animals in the Cenozoic Era contributed to the spread of grasses. Without large grazers, fire-cleared areas are quickly colonized by grasses, and with enough rain, tree seedlings. Trees eventually outcompeted most grasses. Trampling grazers kill seedling trees but not grasses.

There are about 12,000 grass species in about 771 genera that are classified into 12 subfamilies.

Grasses are, in human terms, perhaps the most economically important plant family. Their economic importance stems from several areas, including food production, industry, and lawns. They have been grown as food for domesticated animals for up to 6,000 years and the grains of grasses such as wheat, rice, maize (corn) and barley have been the most important human food crops. Grasses are also used in the manufacture of thatch, paper, fuel, clothing, insulation, timber for fencing, furniture, scaffolding and construction materials, floor matting, sports turf, and baskets.

Agricultural grasses grown for their edible seeds are called cereals or grains (although the latter term, agriculturally, refers to both cereals and legumes). Of all crops grown, 70% are grasses. Three kinds of cereal—rice, wheat, and maize (corn)—provide more than half of all calories consumed by humans. Cereals constitute the major source of carbohydrates for humans and perhaps the major source of protein, including rice (in southern and eastern Asia), maize (in Central and South America), and wheat and barley (in Europe, northern Asia, and the Americas).

Sugarcane is the major source of sugar production. Additional food uses of sugarcane include sprouted grain, shoots, and rhizomes, and in drink, they include sugarcane juice and plant milk, as well as rum, beer, whiskey, and vodka.

Lemongrass is a grass used as a culinary herb for its citrus-like flavor and scent.

Many species of grass are grown as pasture for foraging or as fodder for prescribed livestock feeds, particularly in the case of cattle, horses, and sheep. Such grasses may be cut and stored for later feeding, especially for the winter, in the form of bales of hay or straw, or in silos as silage. Straw (and sometimes hay) may also be used as bedding for animals.

In the industry, grasses are used as raw material for a multitude of purposes, including construction and in the composition of building materials such as cob, for insulation, in the manufacture of paper and board such as Oriented structural straw board. Grass fiber can be used for making paper, and for biofuel production. Bamboo scaffolding is able to withstand typhoon-force winds that would break steel scaffolding. Larger bamboos and Arundo donax have stout culms that can be used in a manner similar to timber, Arundo is used to make reeds for woodwind instruments, and bamboo is used for innumerable implements.

Common reed is important for thatching. Reeds are used in water treatment systems, in wetland conservation and land reclamation in Afro-Eurasia.

The front of a building normally comprises grasses as the primary plant, used in lawns, which themselves derive from grazed grasslands. They also provide an important means of erosion control (e.g., along roadsides), especially on sloping land. Grass lawns are an important covering of playing surfaces in many sports, including football (soccer), American football, tennis, golf, cricket, softball, and baseball. In some sports facilities, including indoor domes and other places where maintenance of a grass field would be difficult, grass may be replaced with artificial turf, a synthetic grass-like substitute.

In cricket, the pitch is the strip of carefully mowed and rolled grass where the bowler bowls. In the days leading up to the match, it is repeatedly mowed and rolled to produce a very hard, flat surface for the ball to bounce off.