Poaceae family is distributed throughout the world. It has 600 genera and 10,000 species. There are 158 genera and 492 species of this family in Pakistan. three major characteristics of the Poaceae or grass family separate them from other plant families. it is the combination of three characteristics of the grass family.
- Triticum vulgare, wheat
- Zea mays, corn
- Avena sativa, oat
- Oryza sativa, rice
- Bambusa, bamboo
- Saccharam officinarum, Sugar cane.
Vegetative Charachteristics of Poaceae
Poaceae also is known as Gramineae have some unique characteristics than other families. usually known as grass family, have 12 subfamilies, about 600 genera, and some 10,000 or more species.they are arranged in spikelets, each has one or more florets. the spikelets consist of two or fewer bracts at base.
perianth reduced to two scales( Calle lodicules) expand and contract to spread the lemma and palea. there are some more charachteristics are given bellow:
- Habit: Annual or perennial herbs.
- Stem: It is jointed and usually hollow at the internodes. It is closed at nodes.
- Leaves: Leaves are solitary at node. They are sometimes, crowded at the base of the stem. These leaves are simple, alternate, exstipulate and mostly sessile. The leaf bases are mostly sheathing.
- Poaceae or grassland are dominated plant communities.
- they are considered the most important plant family to human, infact humans are mostly economically dependent on these communities.
- Poaceae are contribute to human development as staple food grains, animal grasses, cereal crops, lawn and forage grasses, bumboo ( widely used for construction).
Inflorescence in Poaceae
Their inflorescence is compound. The unit of its inflorescence is called spikelet. These spikelets are variously arranged.
- They may form dense clusters as in wheat compound spike.
- They may be arranged on a branched axis-p3n’cle as in spikelets of oat.
The spikelets are arranged on a slender axis called rachilla. Each spikelet consists of bracts. The lower two empty bracts are called glumes. The glumes cover whole of the spikelet.
The upper bract is called lemma. It encloses the flower. A hyaline scale like bract is present opposite to lemma. It is called palea. This whole structure consisting of lemma, palea and flower is called floret. The glumes or lemmas also contain one or more bristle like structures called awns.
This basic pattern of spikelet is present in all the members of this family. The spikelets of grasses vary in different genera. However; they have different number of fertile florets and different number of sex organs in them.
Flower: Flower is usually bisexual (sometimes unisexual), small, inconspicuous, sessile, bracteate, incomplete, zygomorphic and hypogynous.
Perianth: It is absent or it is represented by 2 (rarely 3) scales called lodicules. These lodicules are hyaline or fleshy.
Androecium: They have 1 to 6, mostly 3, free stamens. They have delicate filaments. While, their anther is versatile.
Gynoecium: They have a compound pistil with three united carpels. Only one carpel is functional. However; stigma usually large and feather like.
Fruit: There fruits are grains or caryopsis. Caryopsis is a dry indehiscent fruit in which fruit wall (pericarp) is completely fused with the seed coat.
Economic Importance of Poaceae
This family has greater importance than all other families of the flowering plants. Although; it has importance both for man and animals.
- Food: All the cereals and millets belong to this family. These form the basic food of mankind. These plants are:
- Tirticum sp (Wheat)
- Avena sativa
- Zea mays (corn)
- Oryza sativa (rice)
- Hordeum vulgare (barley)
- Scale cereale (rye)
- Penlsetum typholdeum
- Sorghum vulgare
- Fodders Most of the fodders of the animals also belong to this family.
- The dried stems and leaves of the cereal crops are used as fodder for the cattle.
- Sugar: Sugar ¡s obtained from the juice of Saccharum officinarum (sugar cane).
- Ornamental plants: Many gras.es are used ¡n lawns, e.g. Agrostis,
- Poa, Festuca etc. So these plants have ornamental significance.
- Used of Bamboo Bambusa (bamboo): These are used as building material.
- These are used for thatching huts making boats, carts pipes etc. Their spilt stems are woven into mats, fans, hats and course umbrella. While, their leaves are given to horse for curing cough and cold.
- Aromatic oils: Certain grasses give aromatic oil e.g. Cymbopogon squarrosus (lemon grass). It gives lemon grass oil.
- This oil is used in perfumes and soap industry for making infusions.
- Paper Industry: Some species of grasses are used for making papers.
- Alcohol and beverages: Ethyl alcohol and many other beverages are prepared form cereals. For example, whisky is prepared from rye, corn and rum molasses form sugar cane.
- Ropes: Fibers are obtained from the leaves of Saccharum munja. However, these fibers are used for making ropes
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