Grasses are in the family Gramineae which has been re-named by
modern botanists as Poaceae. Most grasses are herb-like (soft
wooded) but a few are woody, notably the bamboos. There are 650 genera and
10,000 species widely distributed throughout the world. Of these 50 genera and
160 species are indigenous or naturalized in Britain.
Vegetative structure
a) Stems: Stems of grasses are
termed Culms which are usually hollow along their internodes
and solid at the nodes (joints). The stems may be pithy among certain crop
plants e.g. maize, sugar cane and Indian millet. The grass stem is divided into
sections by bulbous nodes. Some grasses bend at these nodes in a knee-like
fashion.
b) Leaves: The leaves are arranged alternately up the Culm
or stem emerging from the nodes. The leaf blade invests the Culm with its
sheath, the two edges of the leaf overlapping to form a closed tube.
The upper part of the leaf or blade is long and narrow with parallel veins. The
blades may be "gutter shaped" or flat, sometimes in-rolled when
young. Grasses that are adapted to dry conditions sometimes 'in-roll' their
leaves to cut down water loss—the native dune grass, marram grass being a good
example.
c) Ligules and auricles: At the base of the leaf blade of many
but not all grasses there is a columnar appendage know as a Ligule
to be found at the point between the blade and the sheath which surrounds the Culm
or stem. In other grasses there are pointed outgrowths known as Auricles
that are found at the base of the blade which invest the Culm. These features
are often used to distinguish one grass from another when they are not in
flower.
Vegetative
Reproduction and Regeneration
Many grasses, when cut, develop new side shoots to give a tuft effect while
other grasses notably couch grass have creeping underground stems which makes them successful colonizers. Most
grasses are perennial though a few are annual e.g. annual meadow grass which
flowers fully before it dies. The roots of all grasses are Adventitious
unlike some plants which have fibrous or tap-roots. Grasses regenerate rapidly
and are the most dominant forms of natural vegetation covering the surface of
the earth.
Rye
Cereal
grass (Secale
cereale) and its edible grain, used to make rye bread and rye whiskey, as
livestock feed, and as a pasture plant. Native to South Asia, today it is grown
extensively in Europe, Asia, and North America. It is planted mainly where
climate and soil are relatively unfavourable for other cereals and as a winter
crop where temperatures are too cold for winter wheat. Rye thrives
at high altitudes and is the most winter-hardy of all small grains. It is high
in carbohydrates and provides small quantities of protein, potassium, and B
vitamins. Only rye and wheat have the necessary qualities to make a loaf of
bread, but rye lacks the elasticity of wheat and thus is frequently blended
with wheat flour. The tough fibrous straw of rye is used for animal bedding, thatching,
mattresses, hats, and paper. Rye may be grown as a green manure
crop.
Oats
An agricultural crop grown for its grain and straw in most
countries of the temperate zones of the world. In the major oat-growing states
of the midwestern United States (Iowa, North Dakota, South Dakota, Minnesota,
and Wisconsin) the crop is raised for grain, whereas in the Southern states
(Texas, Oklahoma, and Georgia) it is used for pasture or a
combination of pasture and grain. About 90% of the annual oat grain production
is used for animal feeds, and about 10% is processed into food for humans, for
example, oatmeal
and other cereal
products. In general, oats are a cool-season crop which requires a moist climate.
They grow well on both light and heavy soils if sufficient moisture and
fertility nutrients
are available.
This is an annual
cereal grass with a fibrous root producing a smooth, hollow, jointed stem,
growing up to 120cm tall, with more or less rough pale green, narrow flat
leaves. The flowers are arranged in a loose terminal panicle from 15-30cm long
consisting of two-flowered spikelets up to 2.5cm long. The hairy, grooved grain
is narrow with almost parallel sides.
Corn
Cereal plant (Zea mays)
of the family Poaceae (or Gramineae). It originated in the New World and has
been introduced globally. American Indians taught colonists to grow corn,
including some varieties of yellow corn that are still popular as food, as well
as varieties with red, blue, pink, and black kernels, often banded, spotted, or
striped, that today are regarded as ornamental and in the U.S. are called
Indian corn. The tall, annual grass has a stout, erect, solid stem and large
narrow leaves with wavy margins. Corn is used as livestock feed, as human food,
and as raw material in industry. Though it is a major food in many parts of the
world, it is inferior to other cereals in nutritional value. Inedible parts of
the plant are used in industry — stalks for paper and wallboard; husks for
filling material; cobs for fuel, to make charcoal, and in the preparation of
industrial solvents. Corn husks also have a long history of use in the folk
arts for objects such as woven amulets and corn-husk dolls. Corn is one of the
most widely distributed of the world's food plants. In the U.S. corn is the
most important crop, but slightly more acres of soybeans are planted.
Wheat
Any of various cereal grasses in the
genus Triticum of the Poaceae (or Gramineae) family, one of the oldest
and most important of the cereal crops. More of the world's farmland is devoted
to wheat than to any other food crop; China is the largest wheat producer. The
plant has long, slender leaves, hollow stems in most varieties, and flowers
grouped together in spikelets. Of the thousands of varieties known, the most
important are T. aestivum, used to make bread; T. durum, used in
making pasta; and T. compactum (club wheat), a softer type used for
cake, crackers, cookies, pastries, and household flours. Winter wheat (sown in
fall) and spring wheat (sown in spring or, where winters are mild, sometimes
fall) are the two major types. The greatest portion of wheat flour is used for
breadmaking. Small quantities are used in the production of starch, malt,
gluten, alcohol, and other products. Inferior and surplus wheats and various
milling by-products are used for livestock feeds.
Barley
Annual cereal plant (Hordeum vulgare and sometimes other species) of the
family Gramineae (grass family), cultivated
by humans probably as early as any cereal. It was known to the ancient Greeks,
Romans, Chinese, and Egyptians and was the chief bread material in Europe as
late as the 16th cent. It has a wide range of cultivation and matures even at
high altitudes, since its growing period is short; however, it cannot withstand
hot and humid climates. Today barley is typically a special-purpose grain with
many varieties rather than a general market crop. It is a valuable stock feed
(often as a corn substitute) and is used for malting when the grain is of high
quality. It is a minor source of flour and breakfast foods. Pearl barley is
often used in soups. In the Middle East a limited amount of barley is eaten
like rice. In the United States most spring barley comes from the western
states and most winter barley is grown in the southeastern states for autumn
and spring pasture and as a cover crop. Barley is subject to several diseases
including smut and rust. Barley is classified in the division Magnoliophyta, class
Liliopsida, order Cyperales, family Gramineae.
Sorghum
Sorghum vulgare, S. bicolor; cereals that thrive
in semi-arid regions and provide important human food in tropical Africa,
central and north India, and China. Sorghum produced in the USA and Australia
is used for animal feed. Also known as kaffir corn (in South Africa), guinea
corn (in west Africa), jowar (in India), Indian millet, and millo maize. The
white-grain variety is eaten as meal; the red-grained has a bitter taste and is
used for beer; sugar syrup is obtained from the crushed stems of the sweet
sorghum. A 200-g portion is a rich source of
protein, vitamin B1, niacin, and iron; a good source of zinc; a
source of vitamin B2; provides 14 g of dietary fibre; supplies
660 kcal (2800 kJ). See also millet.