Differentiating sedges (Cyperaceae members) and grasses: Grasses can be easily  differentiated from other families, particularly in habit and in character of leaves, fruits, seeds and embryos. They are predominantly herbaceous, the woody bamboos being exceptions. Members of Cyperaceae share some of the common characteristics of grasses as they are their nearest relatives. Both are having herbaceous habit, with small flowers without sepals and petals. The flowers arise from the axils of boat shaped scales called glumes. The glumes are arranged in small units called spikelets. Each such spikelet may have a single flower as in rice, two in sugarcane or numerous as in many other grasses. However table 8.11 below shows the dissimilarities between sedges and grasses.

Table 8.11: Sedges vs. grasses

Vegetative and floral morphology of grasses - The vegetative parts:

Habit: Grasses vary very much in their habit. Some grasses grow erect forming tufts and others form cushions with their branches creeping along the ground. Some grasses are annual while others are perennial. It is often difficult to determine whether a certain grass is annual or perennial. But by examining the shoot system this can be ascertained easily. In an annual all the stems and branches usually end in inflorescences and they will be of the same year. If, on the other hand, both young leafy branches and old branches ending in inflorescence are found mixed, it is a perennial grass. The presence of the remains of old leaves, underground stolons and rhizomes are also signs of perennial grasses.

Roots: Grasses being monocots do not produce tap roots. Their roots are tufts of fibrous structures from base of stems or from nodes of creeping stem. Grasses also might produce from nodes of horizontal branches aerial roots. Stilt like aerial roots from basal nodes of stout, tall stems are characteristic of Andropogon, Sorghum (Jowar), Zea (maize), Saccharum (sugarcane) etc. The root systems of the most grasses are superficial on the soil and so are best adapted for absorbing water and nutrients from top soils.

Stem: In annual grasses stems in most cases are erect or even if they are not entirely so they become erect at the time of flowering. But in perennials in addition to erect branches, creeping branches, stolons, and rhizomes may occur. The internodes in most cases are usually hollow. The younger parts of stems especially are protected sheathing base of leaves.  Nodes may be pale or colored, glabrous, hairy or bearded with long hairs.

Leaf: Leaves are in two rows alternating left and right on the nodes of the stem. Leaves may be crowded towards stem base forming tufts, in many perennial grasses. The leaves are reduced to non-green scaly structures in the lower nodes in some of the grasses. The normal foliage leaves of grasses consist of two parts, the flat expanded portion called the blade and the lower part called the sheath that encircles the stem above the node. At the junction of sheath and blade is a scaly outgrowth called ligule. The ligule may be reduced to a tuft or fringe of hairs. The function of the ligule is probably to facilitate the shedding of water which may run down the leaf, and thus lessen the danger of rotting of the stem. The veins in the leaf blade can usually be seen running closely parallel from base to tip.

Inflorescence and flower: The flowers of grasses are reduced to just their reproductive parts the stamens (male) and pistil or gynoecium (female reproductive). The ovary of the pistil matures into the fruit containing the seed inside it. The flowers are aggregated together on distinct shoots constituting the inflorescence.  Sooner or later all the branches of a grass-plant terminate in inflorescences which usually stand far above the foliage leaves. Inflorescences are of different types but its basic unit is called spikelet. In a spike inflorescence, as in ragi, spikelets are directly attached to the axis without a stalk. Raceme is like a spike but the spikelets are attached by stalks as in wheat. A branched inflorescence axis as in rice is a panicle. The spectacular, silken and fluffy white sugarcane inflorescence, for instance, is a large panicle.

The spikelet may be considered as a specialized branch consisting of a short axis, the rachilla bearing a series of scaly bracts, the glumes, the lowest pair being empty but the others bearing flowers in their axils (Figure 9.1). The lower two bracts are empty and are called glumes; above the glumes are one or more boat shaped bracts called lemma, arranged alternately towards right and left of the axis. The flower in the axil of lemma is closed by yet another bract like structure called ‘palea’.

Figure 9.1: Dissected spikelet of Arundinella metzii showing different parts

The grasses are self pollinated or wind pollinated and therefore they have no necessity of producing colorful flowers or nectar to attract butterflies or bees. Probably grasses were once, in their early stages of evolution attractive flowers. Today, most grasses still have two or three tiny ‘lodicules’ at the base of the ovary, which represent vestigial perianth. The stamens are three in number in majority of grasses and six are in rice, Hygroryza and bamboos. In mature flowers the stamens protrude out of the glumes and oscillate in the wind on their delicate stalks called filaments. The anthers produce plenty of pollen which are carried away by wind, the pollinating agency. The pistil consists of a bulged ovary topped with two delicate styles ending in feathery stigmas that are suited for capturing wind borne pollen. Ovary has just one chamber and a single ovule attached to its base.

Fruit: Typical fruit is usually a caryopsis, a dry one, where the seed cover is fused with the thin fruit wall constituting what is known as bran. The fruit covered by the husk which consists of two scaly and concave glumes, which were the original protective cover of the flower. Fruit is sometimes a nut, if the hard fruit wall is free from seed coat; fruit is a utricle if the fruit wall is membrane like and free from seed coat; in rare cases fruit may be a tiny, fleshy berry. The seed is with starchy endosperm and small embryo at base of it.

Pollination: Grasses in general are wind pollinated, though in few cases like rice self pollination occurs. Jowar has a combination of self and cross pollination. The terminal position of the inflorescence, its protrusion far above the level of the foliage leaves, the swinging and dangling anthers, the abundance of non-sticking pollen and the plumose stigmas are all intended to facilitate pollination by wind.

General aspects of flowering and fruiting: The beginning of monsoon in early June triggers germination and luxuriant growth of grasses and the Tiger Reserve in many places turn into green carpet of rolling grasslands. For most annual grasses of the Reserve flowering and fruiting start from late August, with some decline in the intensity of South West Monsoon. Flowering and fruiting are profuse from September and go on almost to January. Some of the perennials and wetland species in favorable moisture conditions, flowering and fruiting occur almost throughout the year. 

Grassland communities: Although grasses are dominant, the grassland community includes also large number of other herbs from dicot and monocot families. The fodder quality of these herb communities also count in judging the forage importance of the grasslands. In many overgrazed pastures weedy and unpalatable herbs such as members of Asteraceae viz. Chromolaena, Ageratum, Parthenium etc., multiply at the expense of the original palatable herbs such as sedges, Justicia, Rungia, Phyllanthus, Desmodium, Alysicarpus, Crotolaria etc. This brings down the overall quality of the grasslands to support herbivores. Hence grasslands need to be managed to their best combinations of species diversity and biomass, in the interest of wildlife promotion, through periodic surveys and management interventions. Details regarding the other herbs noticed in the transect studies in the grasslands of ADTR are given in the Appendix 2 and 3 respectively.