GKAMINKA'K 



subtended or enclosed by a pair of outer scales (glumes): perfect floret consisting of 

 a sessile ovary bearing two (rarely 1 or 3) feathery stigmas, usually 3 stamens with 

 delicate filaments, and two (rarely 3) small hyaline scales (lodicules) representing the 

 perianth, enclosed by lemma (outside) and palea (inside, next to the rachilla): fruit a 

 caryopsis (grain) in which the ovary wall and coat of the single seed are united. 

 About 600 genera with over 6,000 species, cosmopolitan; about 160 genera and 600 

 species in China. 



For the benefit of students beginning their study of the grasses, Mrs. Chase has 

 kindly prepared in non-technical language an introduction to the special terms used 

 in descriptions for this family. She has also provided her own drawings illustrating 

 the complicated structures involved. 



INTRODUCTION TO GRASSES 

 By Agnes Chase 



The grass family is one of the largest families of plants and is the most widely 

 distributed one. It consists of more than 650 genera, including the 38 or more genera 

 of bamboos. To facilitate study of so great a number the grasses have been divided 

 into 14 tribes, all of them represented in the flora of the Lower Yangtse. 



The flowering parts of grasses differ greatly in general appearance from the 

 flowering parts of other plants and it is necessary to understand their structure in 

 order to study the grasses. Fig. A shows a grass stem, called the culm, made up of 

 a series of nodes and internodes, the nodes (joints) solid, the internodes usually hollow, 

 enclosed in a sheath, which surrounds the culm like a tube split down one side, and 

 with a blade which is usually strap-shaped, flat or with rolled margins. The sheath 

 and blade form a specialized leaf, and the leaves are borne in 2 ranks, alternate, on 

 opposite sides of the culm. At the junction of sheath and blade on the inside is a 

 small scale or row of hairs, called the ligule. The root, stem, and leaves are the 

 vegetative parts of the plant. (See Fig. A). In grasses the vegetative parts are more 

 uniform and characteristic than in most other families. Having stem and leaves it 

 can be readily decided whether or not a given plant is a grass. (The only plants that 

 may reasonably be mistaken for grasses are the sedges. In these the culms are solid, 

 not jointed, and are commonly 3-sided; the leaves are always 3-ranked and the sheaths 

 always closed.) 



The flowers of grasses are small and inconspicuous. They consist of a single 

 pistil with a 1-celled ovary with a single ovule, with 2 styles, each with a feathery 

 stigma (1 in Zea mays, elongated and stigmatic over the surface), and 3, (rarely 1 or 

 6) stamens with delicate filaments and 2-celled anthers. Two minute scales {lodicules), 

 situated back of the pistil become turgid at blooming time and force open the envelop- 

 ing scales. Grasses are wind-pollinated (Fig. B). 



The grass flower is reduced to the essential organs, the calyx wanting and the 

 corolla represented by the minute lodicules. This reduced flower is subtended by a 

 2-nerved bract (the palea) and is borne in the axil of a second bract (the lemma). 

 The flower, with its lemma and palea is termed the floret. (Fig. C.) 



The ripened ovary (the grain or caryopsis (Fig. D)) consists of a small embryo 

 lying at the base of a mass of starchy endosperm, which is the store of food used by 

 the infant plantlet when it begins to grow. (The germ of a kernel of corn is the 

 embryo, the remainder of the kernel is starchy endosperm.) 



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