Cytologia 39: 561-571 , 1974

Studies on the Cytology and Phylogeny of South Indian Grasses II. Sub-family Eragrostoideae

J. Christopher and A. Abraham1

Departmentof Botany,University of Kerala, Trivandrum, ReceivedFebruary 22, 1973

Introductory remarks, materials and methods and cytological observations and their bearing on 24 species belonging to 16 genera were described in the previous paper (Christopher and Abraham 1971). The present paper deals with cytological studiesmade on 29 species belonging to the subfamily Eragrostoideae.

Subfamily V-Eragrostoideae

This is one of the three large subfamilies of the Gramineae. The cytology of

29 species belonging to 15 genera, representing the tribes, Eragrosteae, Chlorideae , Pappophoreae and Zoysieae is reported in this paper.

Tribe 1: Eragrosteae

Cytology of 13 species belonging to 4 genera of this tribe has been studied. Eragrostis tenella (Linn.) P. Beauv. This slender, tufted, annual grass, occurs throughout the plains of India. There is no previous report on the cytology of this species. Meiosis showed 30 bivalents at metaphase I (Fig. 1). E. unioloides (Retz.) Nees

An annual grass very abundant in wet places on the hills and plains. The inflorescences are very variable in colour and size. This species was collected from Malampuzha. Meiosis was regular with 10 bivalents at metaphase I (Fig. 2). In somatic mitosis 20 chromosomes which range in length between 1ƒÊa and 2ƒÊ were seen (Fig. 3). The cytology of this species is also studied for the first time. E, diplachnoides Steud.

This perennial grass grows gregariously in damp soils near the banks of rivers and streams and was collected from Mahendragiri. Cytology of this species has not been investigated previously . Mitosis has shown 20 chromosomes which range in length between 1 .5ƒÊ and 3.5ƒÊ (Fig. 4.). E. pilosa (Linn.) Beauv

This is a densely tufted slender annual grass, which occurs in wet places all over India and in most warm countries . Ono and Tateoka (1953) have reported the chromosome number of this species as 2n=40 . The present study of meiosis confirms the above count; 20 bivalents are observed in pollen mother cells (Fig . 5).

E. atrovirens (Desf .) Trin. 1 Present address: Prof . A. Abraham, FAO Regional Headquarters for P. B. No. 1628, Accra , Chana, W. Africa. 562 J. Christopher and A. Abraham Cytologia 39

Figs. 1-17. Photomicrographs of chromosomes of grasses. All figures are reproduced at a magnification of•~1,000. 1, first meiotic metaphase in Eragrostis tenella (Linn.) Beauv. n=30. 2, metaphase I of meiosis in Eragrostis unioloides (Retz) Nees. n=10. 3, mitosis in a root tip cell in the above species. 2n=20. 4, Eragrostis diplachnoides Steud. 2n=20. 5, Eragrostis pilosa (Linn.) Beauv. Diakinesis showing 20 bivalents. 6, mitosis in Eragrostis atrovirens (Desf.) Trin. 2n=60. 7, diakinesis in a pollen mother cell of Eragrostis nutans (Retz.) Nees showing 1974 Studies on the Cytology and Phylogeny of South Inidan Grasses II 563

This is a tufted perennial grass occurring in moist places and sometimes as an

aquatic. Material for the present study was collected from Mahendragiri. Root

tip cells showed 60 chromosomes which ranged in length between 1.5ƒÊ to 2.5ƒÊ

(Fig. 6). Pienaar (1955) and de Wet (1960) have reported the chromosome number of this species to be 2n=40. E. nutans (Retz.) Nees This is a sporadic grass, very common in pasture grounds. There is no previous

report on the cytology of this species. Meiosis was regular and 30 bivalents were observed in pollen mother cells (Fig. 7).

E. tremula Hochst. This is a perennial grass with sub-erect stems, 6•L•Lto 3•L in height. It is common

in sandy places and material for this study was collected from Aryankavu. Mulay and Leelamma (1956) reported the chromosome number of this species as 2n=20.

During the present study, 20 bivalents were counted at meiotic metaphase (Fig. 8). E. japonica (Thunb.) Trin. A perennial erect grass with glabrous stiff stems, up to 3 ft in height. The

panicles are long, stout, about 1 ft long, and interrupted with many tiers of rather short-spreading branches. This grass is found in India, Ceylon, tropical and Africa. It occurs in Mysore and Kerala upto an altitude of 3,000 ft and was col lected from Kallikkad. Root tip cells showed 60 chromosomes which range in

length between 1.5ƒÊ and 2.5ƒÊ (Fig. 9). Avudulov (1928) reported the chromosome number of this species as 2n=20.

Eragrostiella bifaria (Vahl) Bor It is a densely caespitose perennial grass with long filiform convolute leaves. Squash preparations of root tip cells have shown 18 chromosomes which range in

length between 2ƒÊ and 3ƒÊ with median or submedian constrictions (Fig. 11). There is no previous report on the cytology of this .

Desmostachya bipinnata (Linn.) Stapf This species, commonly known as "Darbha" occurs in India and North Africa. It is a perennial grass with tufted stems branching from the base and with stout

stolons. It is frequently met with in dry places and open waste land. This mono typic genus very closely resembles Eragrostis. There is no previous report on the

cytology of this genus. Material for the present study was collected from Kallikad. Mitosis showed 20 chromosomes in root tip cells (Fig. 10).

Sporobolus diander (Retz.) Beauv.

This tufted perennial grass with slender stems, grows gregariously in the plains and low hills and was obtained from Trivandrum. Preparations of meiosis showed

12 bivalents at metaphase I (Fig . 12). Mitotic studies of root tip cells showed 24 c hromosomes which range in length between 2ƒÊ and 2.5ƒÊ (Fig. 13). Avdulov (1928)

30 bivalents. 8, Eragrostis tremula (Hochst) Steud. Metaphase I of meiosis. n=20. 9, mitosis i n Eragrostis japonica (Thunb .) Trin. 2n=60. 10, Desmostachya bipinnata (Linn.) Stapf. 2 n=20. 11, Eragrostiella bifaria (Vahl) Bor . 2n=18. 12, Sporobolus diander (Retz.) Beauv. Meio sis showing 12 bivalents . 13, mitosis in a root tip cell in the above species. 2n=24. 14, Sporoboluscoromandelianus (Retz .) Kunth. 2n=24. 15, Sporobolus indicus (Linn.) R. Br. Variety I. 2n=40. 16, meiosis in a pollen mother cell of another variety of the above species showing 24 bivalents. 17, Chloris barbata Sw. Meiosis. n=20. 564 J. Christopher and A. Abraham Cytologia 39

Figs. 18-36. Photomicrographs of chromosomes of grasses. All figures are reproduced at a

magnification of•~1,000. 18, mitosis in a root tip cell in Chloris barbata Sw. 2n=40. 19, Chloris incompleta Roth. Mitosis. 2n=40. 20, Cynodon dacylon (Linn.) Pers. 2n=27. 21, Cynodon

arcuatus J. S. Presl. Meiotic metaphase I shwoing 18 bivalents. 22, mitotic chromsomes in a root tip cell of the above species. 2n=36. 23, Cynodon barberi Rang. et Tad. Mitosis in a root tip cell showing 18 chromosomes. 24, Eleusine indica (Linn.) Gaertn. Meiosis showing 9 bivalents at early metaphase I. 25, mitosis in a root tip cell of the above species showing 18 chromosomes. 26, Eleusine coracana (Linn.) Gaertn. First meiotic metaphase showing 1974 Studies on the Cytology and Phylogeny of South Indian Grasses II 565

reported the chromosome number of this species to be 2n=36. S. coromandelianus (Retz.) Kunth It is an annual grass with densely tufted stems which spread closely on the ground. This species cocurs in moist places in the plains and was collected from Mahendragiri. Mitosis showed 24 chromosomes, 12 of which are about 1.5ƒÊ in length while the remaining 12 are about 3ƒÊ in length (Fig. 14). There is no previous report on the cytology of this species.

S, indicus (Linn.) R. Br. This is a widespread species, occurring throughout India, Burma and other

Asian countries and tropical . The culms are tufted and erect and it is very common in the plains and hills upto an altitude of 7,000 ft. Avdulov (1931) reported two somatic chromosome numbers of 2n=18 and 36 and Warmke et al.(1946) have recorded 2n=24 chromosomes in this species. Two varieties of this species were collected from Munnar during the present study. One variety was larger in height, leaf-size etc. and its somatic chromosome number was found to be 2n=40 (Fig. 15). Ten chromosomes are about 1ƒÊ in length while the remaining 30 are about 2.5ƒÊ in length. The other variety also collected from Munnar was comparatively smaller in the above morphological characters. Meiosis showed 24 bivalents at metaphase I (Fig. 16).

Tribe II: Chlorideae The cytology of 12 species belonging to 7 genera of this tribe has been studied. Chloris barbata Sw.

This is a very common grass generally occurring in the tropics and widely dis tributed throughout the plains of India, from sea-level to 2,000 ft. It grows on all kinds of soil and is found in large tufts on pasture grounds, especially on sandy soil.

Meiosis was regular with 20 bivalents at metaphase I (Fig. 17). The somatic chro mosome number was found to be 2n=40. The chromosomes range in length between 1.5ƒÊ and 3ƒÊ and have median or submedian constrictions (Fig. 18). Janaki

Animal (1955) has also reported a somatic count of 2n=40 chromosomes while Avdulov (1928) reported the chromosome number of this species to be 2n=20. C. incompleta Roth

This is a sporadic perennial grass found often in hedges and scrambling among bushes. It occurs in hilly places not exceeding 3,000 ft in elevation and was col

lected from Ponmudi . There is no previous report on the chromosome number of this species. Mitosis showed 40 chromosomes which are small in size, ranging

in length between 1ƒÊ and 2ƒÊ (Fig . 19).

Cynodon dactylon (Linn .) Pers. This species is commonly known as "Bermuda grass" in Australia and as "doub

grass" in India. It is commonly planted as a lawn grass especially in warm regions.

18 bivalents. 27, Dactyloctenium aegypticum (Linn.) Beauv. Diakinesis showing 24 bivalents. 2 8, mitosis in a root tip cell in the above species 2n=48. 29, chinensis (Linn.) Nees 2n=54. 30, bromoides Roem . 2n=20. 31, Tripogon filiformis Nees ex Steud. 2n=20 32, metaphase I of meiosis in thomaeum (Linn.) Trin. showing 10 bivalents. 33, Enneapogonelegans (Nees) Stapf , 2n=20. 34, Zoysia matrella (Linn.) Merr. Diakinesis showingbi 20 valents. 35, first meiotic metaphase in Perotis indica (Linn.) Ktze. showing 20 bivalents. 36, Tragus biflorus Schult. Metaphase I of meiosis showing 10 bivalents. 566 J. Christopher and A. Abraham Cytologia 39

It has strongly developed creeping underground stolons and often surface runners also. Mitosis showed 27 chromosomes in root tip cells. The chromosomes are

about 2ƒÊ 3 pin length, with median or submedian constrictions (Fig. 20). Previous reports on the chromosome number of this species show 2n=40 (Hurcombe 1947

and Tateoka 1953) and 2n=36 (Brown 1950). C. arcuatus J.S. Presl

This grass is widely distributed in the plains of South India and may be seen in the same localities as C. dactylon but less commonly. It differs from the latter in

the absence of rhizomes and the possession of a membraneous ligule (Bor 1960). This species has not been cytologically studied previously. Meiosis was regular

with 18 bivalents in pollen mother cells at metaphase I (Fig. 21). Mitosis showed 36 chromosomes which are small-sized ranging in length between 1ƒÊ and 2.5ƒÊ with

median or submedian constrictions (Fig. 22). C. barberi Rang. et Tad. This grass is less common, though it occurs in the same regions as C. dactylon

and was collected from Marutvamala. Squashes from root tip cells showed 18 chromosomes which range in length between 1.5ƒÊ and 3ƒÊ with median or submedian

constrictions (Fig. 23). Cytology of this species is also studied for the first time . Eleusine indica (Linn.) Gaertn. This is an annual weed, very widely dispersed throughout the tropics. It is

known as "crow-foot grass" in India and as "goose-grass" in North America, where it occurs in the warmer parts. Meiosis was regular with 9 bivalents in pollen mother cells (Fig. 24). Mitosis showed 18 chromosomes in root tip cells (Fig. 25). Avdulov

(1931) reported the chromosome number of this species to be 2n= 18, while Moffett and Hurcombe (1949) reported a somatic count of 36 chromosomes in materials of this species from Africa. E. coracana (Linn.) Gaertn.

This species commonly known as "Ragi" is widely cultivated in India as in other parts of Asia and Africa for its valuable food grain. Meiosis was regular with 18 bivalents at metaphase I (Fig. 26). Avdulov (1931) reported the chromosome

number of this species to be 2n=36.

Dactyloctenium aegypticum (Linn.) P. Beauv.

This species is a sporadic annual, with creeping branches and occurs as a weed in cultivated paddy fields and open grounds. It is spread throughout the tropical and subtropical regions and is considered to be a very nutritious fodder for cattle.

Meiosis showed 24 bivalents at diakinesis (Fig . 27). Root tip cells showed 48 chro mosomes which are small sized and thirty chromosomes range in length between

1ƒÊ and 1.5ƒÊ while the remaining 18 are about 3ƒÊ in length (Fig . 28). Avdulov

(1931) has also reported a somatic count of 2n=48 chromosomes for this species while Moffett and Hurcombe (1949) have reported 2n=36 . Leptochloa chinensis (Linn.) Nees

It is a tall annual grass about 2-4 ft in height with a creeping root-stock. This species is very common in paddy fields and wet situations and occurs throughout

India, Ceylon, China, Japan and Australia. Material for the present study was collected from Trivandrum. Root tip squashes showed 54 chromosomes which 1974 Studies on the Cytology and Phylogeny of South Indian Grasses II 567

range in length between 1ƒÊ and 2.5ƒÊ (Fig. 29). Avdulov (1928) has recorded the chromosome number of this species to be 2n=40.

Tripogon bromoides Roem. et Schult This is a slender, densely tufted grass with erect stems and is common in hilly

areas between 4,000 and 7,000 ft altitude. Materials for study were collected from

Munnar. Cytology of this species is studied for the first time. Mitosis showed 20 chromosomes in root tip cells (Fig. 30). T. filiformis Nees This plant was also collected from Munnar. It closely resembles T. bromoides.

The cytology of this species has not been investigated previously. Mitosis showed 20 chromosomes, ten of which are about 2ƒÊ in length and the remaining 10 are

about 3.5ƒÊ in length and all have median or submedian constrictions (Fig. 31).

Oropetium thomaeum (Linn.) Trin. This species was collected from Marutvamala. It is a very small annual short lived grass, common in the plains of India. The are 2••3••high, and forms

hard tufts on the soil with compressed stems. There is no previous cytological report for this species. Meiosis showed 10 bivalents at metaphase I (Fig. 32). Tribe III. Pappophoreae Cytology of only one species belonging to this tribe has been studied.

Enneapogon elegans (Nees) Stapf This is a perennial grass with erect stems, 1-3 ft in height and having a swollen, woody base. The leaves are narrow and convolute and the spikelets are borne in contracted panicles. It is very common in the plains of the Deccan region and

was collected from Marutvamala. Mitosis showed 20 chromosomes in root tip cells. The chromosomes range in length between 1ƒÊ and 2.5ƒÊ and the constric

tions are median or submedian (Fig. 33). Janaki Ammal (1955) has also reported the chromosome number of this species to be 2n=20. Tribe IV. Zoysieae The cytology of three species belonging to the genera Zoysia, Perotis and Tragus

has been studied. Zoysia matrella (Linn.) Merr. "Manila grass"

It is a sea-side plant, growing on rocks, sand and in salt marshes of tropical Asia. It creeps to a great length and is a good sand-binder. This grass was col lected from Veli. Meiosis showed 20 bivalents in pollen mother cells (Fig. 34). Forbes (1952) has reported a somatic count of 2n=40 for this species.

Perotis indica (Linn.) Ktze.

This annual grass is easily recognized by its purplish or greenish squirrel-tail like inflorescence. It grows in open waste places and dry fields and is very common in sandy tracts, upto an altitude of 5,000 ft. This species was collected from Triv andrum. There is no previous report on the chromosome number of this species. Only meiosis could be studied and 20 bivalents were observed at metaphase I (Fig.

35).

Tragus biftorus Schult . It is a sporadic xerophytic species found in the plains of India and Ceylon, often in sandy localities , upto an altitude of 3,000 ft. This plant was collected 568 J. Christopherand A. Abraham Cytologia39 from Marutvamala. Meiosis was regular and 10 bivalents were observed at meta phase I (Fig. 36). De Wet (1954) has reported the chromosome number of T. ra cemosus (= T. biflorus) as 2n=40.

Discussion Subfamily Eragrostoideae Tribe I. Eragrosteae The present study on this tribe has been confined to 13 species belonging to four genera, viz. Eragrostis, Eragrostiella, Desmostachya and Sporobolus. The cytology of 8 species of Eragrostis has been studied during the present investiga tion and all these species, have chromosomes in multiples of 10. The chromosome numbers of about 73 species of Eragrostis so far reported are in multiples of 10 only (Darlington and Wylie 1955, Carnahan and Hill 1961). According to Brown (1950), this genus is characterised by the basic number 10. Roy (1965) has observed secondary association of bivalents into five groups during meiosis in Eragrostis diarrhena (n=10) and according to her the basic number of Eragrostis is probably 5 and not 10. The cytology of Eragrostiella bifaria (2n=18) has been studied for first time during this investigation. This genus was separated from Eragrostis by Bor (1940) on the basis of morphological characters. The cytological situation in this genus confirms this as the chromosome number in Eragrostiella bifaria (2n=18) is a multi ple of 9, while multiples of 10 only are so far known in Eragrostis. It is probable that Eragrostiella is derived from species of Eragrostis with the diploid number of 20 chromosomes by aneuploidy. In Sporobolus the chromosome numbers of 27 species are so far known and the basic numbers reported are 9 (Brown 1951), 10 and 12 (de Wet 1960). Three species have been studied during this investigation, viz. Sporobolus diander (2n= 24); S. coromandelianus (2n=24) and S. indicus (n=24 and 2n=40). These numbers show two basic numbers 10 and 12. Tateoka (1965) has reported the chromosome number of S. molleri from East Africa as 2n=12. Therefore there are at least three basic chromosome numbers of 6, 9 and 10 in this genus. Two varieties of S. indicus were studied during the present investigation. On variety is larger in plant height, leaf size, panicle length, etc. and its chromosome number is 2n=40. The other variety is smaller in the above morphological characters and meiosis showed its haploid chromosome number as n=24. Therefore these two varieties of S. indicus collected from similar ecological situations have different basic numbers of 10 (2n=40) and 12 (n=24). Bor (1960) remarks that "the Sporobolus indicus complex is one of those puzzling problems in the Indian Gramineae which still awaits a solution". Therefore this species deserves further study. Stapf (1917) included Sporobolus and a few other genera in a distinct tribe, the Sporoboleae and placed this tribe next to the Eragrosteae. These two tribes are closely related on the basis of the similarity of the glumes and lemmas. The tribe Sporoboleae differs from the Eragrosteae in having the number of fertile florets 1974 Studies on the Cytology and Phylogenyof South Indian Grasses II 569 reducedto one per spikelet. Hubbard (1934) also placed Sporobolus in a distinct tribe and he stated that it showed close relationship to Eragrostis and has probably been derivedfrom that genus. Brown (1950) found that most of the American species of Sporobolushave the basic number 9 and according to him this genus is probably derived from Eragrostis which has basic number 10 by a reduction in basic number from l0 to 9. But Stebbins and Crampton (1961) have followed Pilger (1954) in delimiting the tribe Eragrosteae and included the tribe Sporoboleae also in the Eragrosteae. According to Roy (1965), the basic number of Eragrostis is 5. In Sporobolusmolleri (2n=12) from East Africa, the basic chromosome number is 6 (Tateoka 1965). Therefore Sporobolus is probably derived from Eragrostis by a change in basic number from 5 to 6 and the other chromosome numbers found in Sporobolushave probably arisen by polyploidy. Tribe II. Chlorideae Cytological studies on this tribe have been confined to 12 species representing 7 genera, viz. Chloris, Cynodon, Eleusine, Dactyloctenium, Leptochloa, Tripogon and Oropetium. The two species of Chloris, viz. C. barbata (2n=40) and C. incompleta(2n=40) studied during the present investigation, have chromosome numbers in multiples of 10. Gould (1958) has reported two basic numbers, 9 and 10 for this genus. Three species of Cynodon were studied during this investi gation,all of which have multiples of 10. Previous reports show two basic numbers 9 and 10 for this genus (Darlington and Wylie, 1955). In Eleusine the basic number is 9 for all the species cytologically known so far (Darlington and Wylie 1955). The chromosomenumbers of the two species of Dactyloctenium cytologically known so far are multiples of 12. In Leptochloa all previous reports on 7 species are mul tiplesof 10 only (Darlington and Wylie 1955, Gould 1958, 1966), while a new basic number 9 is reported for the first time in Leptochloa chinensis (2n=54) during the present work. In Tripogon and Oropetium chromosome numbers occur in mul tiplesof 10. This tribe is very closely connected with the Eragrosteae and Stebbins and Crampton (1961) follow Pilger (1954) in the delimitation of this tribe. These two tribeshave many common features. There is similarity in the development of root hairs from the epidermal cells of the Chloridoid-Eragrostoid group (Reeder and Van Maltzohn 1953). Leaf-anatomy in these two tribes is of the Chloridoid type (Brown 1958), while embryo has Panicoid vascular system (Reeder 1957). Thereforethe genera included in these two tribes are closely inter-related and there is no agreement among the various systematists in the delimitation of these two tribes. It is probable that these two tribes have originated from the same ancestral stock. TribeIII: Pappophoreae This tribe is represented by Enneapogon elegans (2n=20) in the present study. Previousreports on the cytology of 6 species of this genus show two basic numbers 9 and 10 (Darlington and Wylie 1955, de Wet and Anderson 1956, Gould 1966). Bews(1929) considered this tribe only as a subtribe, the Pappophorinae under the tribe Festuceae. In the Pappophorinae the lemmas are much cleft and awned and he consideredthis group as the most advanced of all Festuceae in this respect. But 570 J. Christopherand A. Abraham Cytologia39 according to Stebbins and Crampton (1961) who have include this tribe in the Era grosteae, the Pappophoreae differs from typical Eragrostoideae only in a few charac ters like the presence of many-nerved lemmas and in possessing unicellular hairs. This tribe is closely related to the Chloridoid-Eragrostoid group cytologically also as the basic chromosome numbers in Enneapogon are 9 and 10. Their high specialisation shows they are highly advanced members of the Eragrostoideae. Tribe IV: Zoysieae The present cytological study in this tribe has been confined to three species representing the genera Zoysia, Perotis and Tragus. The chromosome numbers recorded are 2n=40 in Zoysia matrella and Perotis indica and 2n=20 in Tragus biflorous. Hackel (1887), Hooker (1897) and Avdulov (1931) included this tribe in the subfamily Panicoideae. Stapf (1917) and Bews (1929) placed this tribe near the Agrostideae in the subfamily Pooideae. De Wet (1960) reported that embryo anatomy and leaf-anatomy in this tribe are typical of the Chloridoid-Eragrostoid type. The cytological situation in this tribe also confirms this view as the most common basic number in this tribe is 10. Both floristically and ecologically the Zoysieae are a very advanced tribe adapted to the dry conditions in the warmer parts of the world.

Summary This paper deals with cytological observations made on 29 species belonging to 15 genera of the subfamily Eragrostoideae. This includes first reports on 14 species. The basic chromosome numbers recorded are 5, 6, 9, 10 and 12. The existence of two cytological types has been observed in Sporobolus indicus. The present cytological findings justify the separation of the genus Eragros tiella from Eragrostis by Bor (1940) on the basis of morphological characters. Sporo bolus is probably derived from Eragrostis by alterations in basic chromosome number as suggested by Brown (1950). The tribes Eragrosteae and Chlorideae are closely interrelated and it is probable that these two tribes have originated from the same ancestral stock. The Pappophoreae and Zoysieae are highly specialised members of the Chloridoid-Eragrostoid group.

Acknowledgment Our thanks are due to the Ministry of Education, Government of India for the award of a Senior Research Scholarship to one of us (J. Christopher) and the Uni versity of Kerala for the very good research facilities. We wish to acknowledge the suggestions and helpful criticism made by Dr. C. A. Ninan, Professor of Genetics and Plant Breeding and Head of the Department of Botany at various stages in this work.

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