In this article we will discuss about the Classification of Glumiflorae. According to Engler and Prantl, Glumiflorae consists of two families:- 1. Gramineae 2. Cyperaceae.
Family # 1. Gramineae (Poaceae):
Gramineae are annual or perennial herbs, rarely shrubby or attaining the size of trees, e.g. the bamboos; some are biennials while some bamboos have life-cycles of 15, 30, 60 or even 120 years; stem is usually un-branched, with hollow internodes and jointed solid nodes; rarely internodes solid, e.g. Saccharum, Sorghum, Zea, etc.
In the case of perennials the stem may be a runner or rhizomatus. The plants are often stoloniferous or may have suckers. Erect portion of the stem which bears the inflorescence is called culm (or haulm). In some species in the region just above the node protected by the leaf- sheath, there is a ring of soft meristematic tissue which becomes active when the stem is laid down upon the ground after a storm.
Due to the activity of the meristem rapid growth is induced on the underside of the stem and it comes to the erect position again. The plants have fascicled or fibrous roots and also in some case adventitious roots and stilt roots.
Leaves are simple, alternate and distichous, sheathed at the base, ligulate. The sheath forms the basal portion of the leaf and encircles the shoot or culm; the margin free and imbricate or united to form a tube. The sheaths are often swollen at the base and this swollen portion is called node of the sheath.
The blade is usually linear and passes imperceptibly into the sheath or is constricted at the base; a distinct petiole is rarely present. Silica-deposit is found on leaves in many species rendering the margins of blade knife-sharp.
The ligule is present at the junction of the sheath and the blade on the inner, i.e. the upper surface of the leaf. This is a membranous outgrowth often represented by a line of hairs. Ligule is absent in Echinochloa. In the Australian genus Micraria the arrangement of the leaves is spiral.
The inflorescence in this family is rather of a very complex type. The basic unit here is a spikelet which bears a few flowers or florets on its axis which is termed the rachilla. The spikelets are on the axis of a spike or raceme or on the branches of a panicle. The inflorescence therefore is mostly of a compound type, i.e. a spike of spikelets, raceme of spike- lets, etc.
The main axis of the inflorescence is called the rachis. A spikelet usually ‘has more than one flower on the rachilla which is very short. The spikelet has a series of alternating scales representing bracts and bracteoles borne in 2 opposite rows, one above the other. The 2 scales at the base are the glumes.
Above the glumes alternating on the rachilla are several pairs of scales, the outer of each pair being the lemma or flowering glume and the inner scale the palea. Each pair encloses a flower. And a flower together with the pair of scales is termed a floret. The lemma is nothing but a bract subtending a flower and palea is a bracteole.
The lemma is also called the lower palea or valve and the palea—the pale, upper palea or valvule. So a spikelet consists of a pair of glumes and one or more florets, and a floret consists of lemma, palea and a flower. The rachilla may terminate in a flower or it may be continued beyond the flowers.
The general interpretation of the morphology of grass-spikelet is as given above. But some botanists consider the spikelet as nothing but a single flower.
According to this view the 2 basal scales are the bracts of the flower and the lemma and palea are segments of outer perianth, i.e., the sepals, the palea representing 2 united segments, the lemma being the 3rd one. Still others think that the lemma and palea are bracts and the lodicules are bracteoles, so that the flower is naked like that in Najadaceae.
The flower may be bisexual or unisexual (monoecious or dioecious), hypogynous. Perianth is represented by 2-3 minute membranous or semi-fleshy scales which are called lodicules. Stamens 3 or sometimes 6, rarely less or more; anthers versatile. Ovary superior, of 3 carpels 2 of which are abortive, unilocular with one campylotropous ovule; styles 2-3 very short with long, feathery stigmas or stigmas sessile.
Fruit is a caryopsis, rarely a utricle or very rarely a berry. Seed with plenty of endosperm and the shield-shaped scutellum lying appressed to the endosperm at the base. The radicle and the plumule are covered by sheaths known as coleorhiza and coleoptile respectively.
Opinions differ as to the real nature of cotyledon. According to Sachs scutellum and the coleoptile are the upper and lower parts of the cotyledon. Van Tieghem on the other hand stated that scutellum is the cotyledon.
The coleoptile and coleorhiza are the sheaths of the plumule and radicle and are stipular in nature. Arber considered that the scutellum and coleoptile represented the single cotyledon.
Avery (1930) stated that the cotyledon was represented only by the scutellum and the coleoptyle was nothing but the second leaf. The flowers are wind-pollinated. The lodicules are hygroscopic and on absorption of moisture they swell up and push apart the palea and lemma exposing the stamens and pistil.
P0 or 2 A3 or 3+3 G1
As described above the compound inflorescence may be a spike or raceme or a branched panicle, rarely forming a globose head as in some bamboos; the female cob of Zea mays is a spadix. Spikelet is one-flowered in Agrostis, Oryza, Anthoxanthum, Andropogon, etc. and the flower is terminal.
Here the basal empty glumes, the fertile glume or lemma and the palea are on one and the same axis, i.e. the rachilla. In the 1-flowered spikelet of Gastridium the floret is lateral and the rachilla extends beyond the flower. Of the two empty glumes one may be absent, e.g. Zoisia, Brachiaria, etc., or both are absent, e.g. Coleanthus. Rarely there are more than 2 empty glumes at the base of a spikelet, e.g. Anthoxanthum.
The palea is usually 2-costate and more or less cleft between the 2 nerves. In some cases it is cleft to the base so that there are 2 paleas each with one midrib. The lodicules are 2-3 in number but in Melica there is only one lodicule. The female flower of Zea mays has no lodicule. In Oclilandra there are many lodicules.
In most of the genera there are 3 stamens in one whorl. In some species of Oryza and many genera of Bambusae stamens are 6 in 2 alternating trimerous whorls. In Microlaena there are two whorls of stamens with 2 stamens in each. In Pariana the male flower has 10-40 stamens. Ochlandra also has many stamens, 6—30 which are in one or several bundles, i.e. monadelphous or polyadelphous.
In most genera there are 2 styles or 2 sessile stigmas. In many bamboos 3 styles are present while in Nardus there is only 1 style with a simple stigma. In Zea the 2 simple stigmas unite to form a single silky thread-like structure.
The majority of the grasses are chasmogamous but some especially those growing in dry areas, are cleistogamous. In such cases flowers remain closed and are self- fertile. The anthers here are very small. Often chasmogamous flowers and cleistogamous flowers occur in the same inflorescences.
The grass seeds are usually very small and light and are dispersed by the wind. The lemma and palea tightly enclose the grain. Sometimes the whole spikelet drops off as a seed. In Eragsostis, Sporobolus and a few other genera the grains are naked.
The seeds are often provided with pappus to help them to be carried away a long distance by the wind. Some seeds have the attached lemma toothed or barbed or provided with bristles and awns. These are dispersed by animals.
Different interpretations of the spikelet and floret of grass give vent to different ideas as to the affinity of the family. Gramineae resembles Cyperaceae in habit. In both the families flowers are very minute and subtended by scaly bracts.
They are in spikelet’s which form the units of a larger compound inflorescence. The two families are considered close to each other and are placed in the same order, e.g. Glumiflorae by Engler.
According to him the lodicules in a grass flower are the bracteoles and all the other scales below the lodicules are bracts. The flower is therefore devoid of perianth and resembles a flower of Najas.
Further he considers that Gramineae is a primitive family because it is wind-pollinated. Rendle supports Engler’s views and following him includes Gramineae and Cyperaceae in one order Glumiflorae and places it after the order Triuridales.
Hutchinson and Wettstein think that Gramineae has been derived from Restionaceae of Juncales which again is derived from Liliaceous stock. Here a grass flower is considered to be a reduction from a pentacyclic flower, where the lodicules represent one of the 2 whorls of perianth, one whorl of stamens remains as a result of suppression of the other whorl and the ovary also tricarpelary but with 2 abortive carpels.
Gramineae and Cyperaceae have some characters common to both, but they differ considerably in other respects. Unlike Gramineae Cyperaceae has a triquetrous solid stem without any nodes, leaves tristichous in arrangement, with closed sheaths and without ligules, anthers basifixed, ovary of 3 united carpels, style one with tripartite stigma and the embryo embedded in endosperm.
Hutchinson therefore puts the 2 families in different orders Cyperales and Graminales and places the 2 orders close to Juncales. Takhtajan also keeps the 2 families in distinct orders and considers Gramineae (Poaceae) is closer to Restionaceae while Cyperaceae is closer to Juncaceae.
Takhatajan thinks that Gramineae and Cyperaceae have been derived from an ancestor from which Commelinaceae originated and not from Liliaceous stock. Cronquist also considers that the 2 families Poaceae and Cyperaceae originated from a Commelinaceous and not Liliaceous stock, but according to him these 2 families are sufficiently closely related to be included in one order as has been treated by Engler.
The family is a large one with about 650 genera and over 10000 species distributed almost all over the globe. Their greatest abundance is in the temperate region although quite a numerous species grow in the tropics. Adaptability to varied ecological conditions enable different species to grow in aquatic situation, fresh as well as brackish water, also in desert areas, in the sea shores and also in alpine regions.
Wherever they grow, numerous individuals are found closely knit together to cover the ground often with the extinction of other plants. There are, however, few grasses that are shade loving but under cover of trees and shrubs or tall herbs most of the grasses thin out and often disappear altogether.
In India there are about 850 species including the bamboos and common among those growing wild are; Cynodon datcylon Pers.— Dubgrass or Bermuda grass, Chrysopogon aciculotus Trin., Digitaria sanguinales Scop., Eragrostis unioloides Nees ex Steud and other species of that genus, Imperata cylindrica (L.) Beauv.—”Ulu”, Saccharum spontaneum Linn.—”Kash”, Coix lachrymajobi Linn.— Job’s tears, Thysanolaena maxima O. Ktz., Sporobolus diander Beauv., Chloris barbata Sw., Dactyloctenium aegipticum (L.) Beauv., Panicum miliaceum Linn and other species of Panicum, Pennisetum typhoidfs Stapf. Hub.—”Bajra”, Vetiveria zizanioides Nash,— “Khas Khas”, Spinifex littoralis Merr.—seashore grass, Hygroryza aristata Nees,—a floating grass, Leersia hexandra Sw.—a marsh-grass found also in mangroves, Festuca valesiaca Schleich and F. undata Stapf—alpine grasses, etc. Indian bamboos are species of Banbusa, Arundinaria, Dendrocalamus, Oxytanthera and Melocanna. The last is the apple- fruited bamboo producing edible berries about 10 cm. long.
The family stands foremost as regards economic importance. It includes the cereals and plants that provide building materials, paper pulp, sugar, medicines, essential oil, etc.
Species, important economically, are noted below:
Oryza sativa Linn—the rice—originated in S. E. Asia; Triticum mono- coccum L., T. dicoccum Schrank, T. aestivum L. and other species of Triticum yield wheat originated in W. Asia and S. E. Europe, Hordeum vulgare L.—the barley originated in C. and W. Asia and N, Africa, Avena sativa L.—Oats of Europe, Secale cereale L.—rye of Europe and Zea Linn.—the Indian corn, originated in C. America.
Most of the grasses are valued as cattle-food. The straw of the cereals are also used in similar manner.
Saccharum officinarum L.—Sugarcane—originated in Indo-Malayan region; Sorghum vulgare Pers. var. saccharatum Koen also yields sugary juice.
Cymbopogum nardus Rendle—Citronella, C. citratus (DC) Stapf. and C. flexuosus Trin. are the Lemon grass, C. martini (Roxb.) Wall—Russa or Palmarosa or Geranium oil grass. Vetiveria zizanivides Nash, also yields a fragrant oil from the roots that are woven into mats which are hung as curtains in doors and windows in the summer months.
Eulaliopsis binata (Retz) Hubb.—”Sabai” grass, Imperata cylindrica (L.) Beauv.—”Ulu” and some bamboos are used in paper manufacturing.
Sacharum munja Roxb., S. arundinaceum Linn, and Imperata cylindrica (L.) Beauv. are used for cordage.
Different bamboos are used for that purpose. Split-bamboos are also used to prepare baskets, tool-handles, etc. For thatching purpose Saccharum spontaneum Linn, and Imperata cylindrica (L.) Beauv. are much in demand.
All grasses yielding essential oil have medicinal value. Tabashir-a siliceous substance, found in certain bamboos is considered a good tonic and astringent. Secale cereale Linn, is the source of ergot which is formed by the infection of the inflorescence by Claviceps purpurea.
Spikelet of Oryza:
Many spikelets in a panicle. Each with 3 flowers of which the terminal one is complete and functional and the lower 2 are abortive represented by their lemma only. The 2 basal glumes are represented by a pair of opposite small swollen bodies or ridges or by very minute scales; these may often be entirely absent.
Above these basal glumes are the lemma of the 1st and 2nd flower in the form of small scales. Above these are the lemma and palea of the fertile flower. The lemma is large and boat-shaped and often awned.
The palea is more or less similar to the lemma and partially enclosed by the same. Lodicules 2 and stamens 6 in 2 whorls with capillary filaments. Styles 2, short, free, with plumose stigma; ovule solitary in unilocular ovary.
The above interpretation of Oryza spikelet is by Stapf and has been widely accepted. The view of earlier workers was that this spikelet is one-flowered having 4 empty glumes below the lemma. The 2 swollen bodies or the ridges are parts of the pedicell. This interpretation is not considered at present to be correct.
Spikelet of Triticum:
Spikelets 2- or more flowered arranged in long spikes, solitary at each node, appressed to the cavities of the rachis which is articulated or not, upper flower male or neuter. Basal empty glumes 2, persistent. Lemma awned or awnless, usually 5-nerved. Palea ciliate on the keel. Lodicules 2, ciliate. Stamens 3. Styles very short.
Spikelet of Hordeum:
Spikelets 1-flowered, 2-3-nate at each node of a long spike in the cavities of the rachis. Basal empty glumes 2, narrow and persistent. The rachilla jointed at the base of lemma and produced beyond it sometimes with an imperfect glume or lemma. Palea 2-keeled. Lodicules 2, entire, ciliate. Stamens 3 or 2. Styles very short.
Spikelets of Zea:
Flowers in Zea are unisexual and are borne in separate inflorescences on the same plant.
This is a terminal branched panicle. The central axis bears several rows of spikelets while the branches have 2 rows of spikelets. The spikelets are paired. One of which is pedicelled and the other is sessile. Each spikelet is 2-flowered and bears 2 empty glumes at the base enclosing the spikelet.
The 2 flowers are alternate, each has a green lemma and a green palea and 2 more or less fleshy lodicules. Stamens 3 in each flower with linear and pendulous anther. A rudimentary ovary is present in the centre. The upper flower matures earlier.
This is a spadix with several rows of spikelets compactly arranged on a fleshy peduncle or cob enclosed by a number of large bracts or spathes. The spadix is axillary and more than one is borne in a plant. The spikelet is 2-flowered the lower one being sterile.
There are 2 empty glumes at the base of the spikelet and the flowers have lemma, plalea and lodicules like the male flowers. Ovary is unilocular with a filiform united style and long hairy stigma that comes out from the top and hangs down like a silk thread. One flower being sterile each spikelet bears only one grain and the grains are closely arranged in rows.
If the growth of the main axis of the plant is arrested at early stage, lateral shoots are produced from the base of the plant. These lateral shoots often produce terminal inflorescences which are bisexual. Male and female spikelet’s may be on different branches of the panicle or may be mixed up.
Subdivisions of Gramineae:
Subfamily I Pooideae:
Spikelets one to many-flowered; spikelets usually break off above the persistent basal glumes at maturity; rachilla continued above the florets. The subfamily is divided into 38 tribes.
Subfamily II Panicoideae:
Spikelets mostly 2-flowered, rarely 1-flowered, breaking off at maturity as a whole with stalk and glumes; rachilla not continued above the florets. The subfamily is divided into 3 tribes.
Family # 2. Cyperaceae:
Cyperaceae are perennial grass-like herbs, rarely annuals, usually with a creeping sympodial rhizome, often tufted; stem solid, triquetrous, without nodes and usually un-branched; rarely stem hollow.
Micro-dracoides is an African woody plant with forked stem, upto 3 mtr in height. Leaves are 3-ranked, usually crowded near base or alternate, sessile, eligulate, with a closed sheath and a long linear blade; very rarely the sheath is split on one side.
Flowers small, bisexual or unisexual in spikelets which form a spike, spike-like cymes, panicles or dense heads; the whole inflorescence or its parts usually subtended by one or more leafy involucral bracts; each flower subtended and enclosed by a chaffy bract or glume, a second glume or bracteole is rarely present.
Perianth absent or represented by scales or bristles, very rarely sub-petaloid. Stamens 3, rarely 6 in 2 whorls or very rarely 1; filaments slender, free, with basifixed anthers.
Carpels 3 or 2, united to form a unilocular ovary with one basal anatropous ovule; ovary superior; style 1 with 3 or 2 plumose stigmas, or stigmas tooth-like. Fruit achene or nut or utricle, compressed or 3-gonous; embryo lying at the base of the seed, surrounded by mealy endosperm.
Germination of seed in Cyperaceae is more or less like that noticed in Palmae (Arecaceae). Here the terminal part of the cotyledon comes out of the seed while the other part remains within the seed and functions as sucker.
Spikelets are several-flowered in most genera but in case of female flowers in Carex and Diplacrum the spikelets are one-flowered. Flowers usually bisexual but unisexual in Carex, Elyna and many genera. The secondary axis of the spikelet extends in the form of a bristle in Uncinia while it bears a male flower above the female in Elyna.
Perianth is represented by bristles in Scirpus and many other genera while they are hair-like in Eriophorum and indefinite in number; in Carex, Cyperns, etc. perianth altogether absent.
In Oreobolus there are 6 scale-like perianth segments in 2 whorls. Stamens are usually 3 but in Rhynchospora and some other genera these are 6 in 2 whorls; in Hemicarpha and Bisboeckelen the androecium is represented by a single stamen.
Tricarpellary or bicarpellary ovary may be found in the same genus or some have only one or the other type. The flower is subtended by a bract; in the pistillate perianthless flower of Carex and Kobresia this bract completely encloses the naked ovary and is called “utricle”; in Kobresia the utricle is split on one side while in Carex it is baglike.
The family contains over 3000 species under about 80 genera and distributed almost all over the world growing in marshes and damp places. About 450 species are found in India from the sea-shores right upto about 3500 mtrs in the Himalayas. Among the Indian species there are many species of Cyperus, Catex, Fimbristylis, etc.
Scirpus littoralis Schrad is common in the mangrove forests. Carex indica Linn, grows on sea- beach and is a good sand-binder. Eriophorum comosum Wall, grows in temperate and alpine Himalayas between elevations of 2000-3500 mtrs. Carex arenaria Linn, occurs in deserts and is an important sand binder.
Plants of this family having economic importance are but few. Cyperus stoloniferous Linn, and C. longus Linn, yield essential oil which is also used in medicine. Cyperus tegetum Roxb., C. corymbosa Rottb and Juncellus inundatus Clarke are used for manufacturing mats.
Cyperus esculentus Linn., Eleocharis tuberosa Schult and Scirpus grossus L.f. var. kysoor Clarke have tuberous roots which are edible. Cyperus rotundus Linn., the “Mutha ghas” is used by Kavirajes to cure disentery.
Cyperus papyrus Linn, has a thick stem about 4 cm in diam. and attains a height of about 3 mtr. This is the paper-reed of the ancient Egyptians who used the long thin strips as writing papers.
Cyperaceae and Gramineae Were considered to be closely allied by Engler as well as Rendle and were included in the same order Glumiflorae. Cronquist also includes the 2 families in the order Cyperales. Hutchinson puts them in 2 monotypic orders, viz. Cyperales and Graminales.
According to him both the families have been derived from Funcales but from different stocks on parallel lines. Wettstein and Takhtajan also treat them similarly. Snell and Blaser also support Hutchinson and state that the spikelets in the 2 families are not homologous.
Subdivisions of Cyperaceae:
Subfamily I Scirpoideae:
Spikelets many flowered; flowers bisexual. Tribes 2, — Scirpeae, Hypoleptreae.
Subfamily II Rhynchosporoideae:
Spikelets one or few-flowered; flowers bisexual or the upper ones male. Tribes 4,—Rhynchosporeae, Gahmieae, Bisboeckelerieae, Sclerieae.
Subfamily III Caricoideaes:
Spikelets many flowered; flowers unisexual; male- flowers often in simple spikes; perianth absent; subtending bract is a utricle. Four genera only.