Cytotaxonomy of the Andropogoneae 1. Subtribes Dimeriinae and Saccharinae

272 Cytologia 21

Robert P. Celarier

Department of Botany and Plant Pathology, Oklahoma A. and M. College, Stillwater, Oklahoma, U. S. A.

Received May 2, 1956 The grass tribe Andropogoneae is considered by many workers (Hartley, 1950, Bews, 1929) to be the most highly specialized of the grasses, and few would disagree with this if the small related group, the Maydeae, were included. The tribe is characteristically tropical and subtropical, although many species of a few genera are found in the temperate regions. The maximum abundance of genera and species is seen in southeast Asia, principally in the Indo-Malaya area (Hartley, 1950). Bews (1929) has proposed that the more advanced grasses are to be found in the drier regions of subtropical grass lands, and the Andropogoneae are very abundant and often dominant in tropical savannahs. The available morphological and geographical information suggests that the tribe is of comparatively recent origin; that it probably originated in the tropical forests of the Indo-Malaya area, and radiated from there to the tro pical savannahs. A few members have advanced into the temperate regions of North America and Eurasia. It is further suggested (Hartley, 1950) that they have not yet reached their full potential in the temperate areas, especial ly in the Western Hemisphere. From these facts one might expect the group to be in an active state of evolution in which many types and all stages of reproductive isolation would be represented. The morphological evidence, as seen in the numerous tax onomic controversies at both generic and specific levels, suggests that in many cases the isolation is not yet complete. In spite of the apparent attractiveness of the group for studies of ex perimental evolution only a few have been made (Mangelsdorf and Reeves, 1939; Reeves and Mangelsdorf, 1942; Randolph, 1955; Garber, 1944, 1950a, 1950b, 1954; Gould, 1953). There is little information on the chromosome cytology of the group and it is the objective of this report to add addi tional cytological information, and to bring together the scattered literature. This review includes the Maydeae although it is considered to be a separate tribe by many workers. It appears to the author that the Maydeae are a natural extension, through specialization, of the Androgoneae and from the standpoint of experimental taxonomy it seems desirable to study them together. 1956 Cytotaxonomy of the Andropogoneae . I 273

Although most taxonomists are in agreement concerning the constitution of the tribe, there is much disagreement regarding the number of genera and species to be included. Hackel (1889), in the first thorough treatment of the tribe, recognized only a relatively few valid genera . In general his system was followed (Hooker, 1897; Trimen, 1900) until the work of Stapf (1919) on the grasses of tropical Africa. Stapf disagreed with Hackel principally in breaking up the latter's genus Andropogon into a number of small genera and in establishing numerous subdivisions. He also added a large number of previously undescribed tropical species. Since Stapf's work most taxonomists working in the tropics, where the tribe is most abundant have, in general , accepted his treatment (Camus and Camus, 1922; Hubbard, 1934; Blatter and McCann , 1935; Keng, 1939; Henrard, 1940; Bor, 1940; Rhind, 1945). On the other hand most tax onomists in the temperate regions have either accepted Hackel's treatment or more frequently a modification of it (Komarov, 1934-45; Hitchcock, 1950; Hegi, 1936; Post, 1933). This is somewhat to be expected since the tem perate zones have so few members of the tribe represented that there is little problem of identification; however, quite the opposite is true in the tropics. The division of the Andropogoneae into subtribes has been treated by many workers (Stapf, 1919; Bews, 1929; Keng, 1939; Pilger, 1940; 1954) since the original work of Hackel (1889). The number of subtribes propos ed varies from four (Bews, 1929) to eight (Keng, 1939), but the must recent treatment (Pilger, 1940; 1954) is somewhat intermediate and includes six. In the present report the proposal of Pilger is followed with occasionally further breakdowns within subtribes for convenience of grouping, and the Maydeae are included. These categories are usually easily separated with the following key:

I. Spikelets perfect, or with staminate, neuter and perfect spikelets mixed in same inflorescence. 1. Spikelets borne singly on axis of the simple raceme and laterally compressed. DIMERIINAE 2. Spikelets borne in pairs on axis of the simple raceme (occasionally the pedicel late spikelet suppressed) and dorsally compressed. A. Joints and pedicels slender, not fused. (1) Spikelets all alike. SACCHARINAE (2) Spikelets of pairs differing in sex. (a) Inflorescence an open panicle, joints and pedicels not grooved SORGINAE (aa) Racemes digitate, binate, or solitary, not a panicle (Capillipe dium has an open panicle but the joints and pedicels have a translucent groove) ANDROPOGONINAE AA. Joints and pedicels stout and often fused to form a receptacle for the sessile spikelet. (1) Fertile spikelets 2-flowered and awned ISCHAEMINAE (2) Fertile spikelets 1-2-flowered, awnless ROTTBOELLINAE *19 274 R. P. Celarier Cytologia 21

II. Spikelets unisexual, the staminate and pistillate in different inflorescences, or different parts of same inflorescence. MAYDEAE

Materials and methods All materials reported on in this study were grown in an experimental nursery at the Oklahoma Agricultural Experimental Station. The nursery is situated on a rather uniform plot of land and each entry was planted in short rows of 18-20 plants. A number of entries failed to flower under our long day summer conditions and two plants from each of these entries were dug up in the fall, transferred to pots, and taken to the greenhouse. Most of these flowered during the short day, winter conditions. Bud material was taken from all entries, fixed in Carnoys fluid, and stored in the refrigerator until studied. Some entries gave good preparations over a year after fixation. Chromosome studies were made of the meiotic divisions using the standard smear technique and staining in acetocarmine. Herbarium specimens of all entries have been placed in the Oklahoma A. & M. College Herbarium and, in most cases, replicates were deposited in the following herbaria: Royal Botanic Gardens Herbarium, Kew, England; University of Pretoria Herbarium, Pretoria, South Africa; Missouri Botanical Garden Herbarium, St. Louis. Missouri; University of California Herbarium, Berkeley, California, and the U. S. National Herbarium, Washington, D. C. The identity of the critical material has been verified by E. R. Sohns of the U. S. National Museum. SUBTRIBEI. DIMERIINAEC. E. HUBB. This subtribe is represented by only one genus, Dimeria. Although a genus of above average size (ca. 20 species) it is restricted geographically to the Indo-Malaya area, China, and North Australia. However, it appears to have been introduced in a few of the Pacific Islands. There is no cytological information for any of the species. This is much needed in view of its isolation from the rest of the Andropogoneae and its supposed primitive phylogenetic position. SUBTRIBEII. SACCHARINAEKUNTH. The subtribe, as described by Pilger (1940), is divided into two groups. One, the Saccharininae, includes Imperata, Sclerostachya, Miscanthns, Ec coilopus, Eriochrysis, Narenga, Saccharum, Spodiopogon, Erianthus and Miscanthidium, and the other, Eulaliininae, includes Ischnochloa, Micro stegium, Apocopis, Polliniopsis, Eulaliopsis, Homozeugos, Eulalia, Pogona therum, Pseudopogonatherum, Lophopogon, Sclerandrium and Polytrias. All of the members of the Saccharininae are treated together by Bews (1929) and Keng (1939), but in the Eulaliininae there are considerable differences in their treatments. Keng in creating a new subtribe, the Apocopeae, places Apocopis, Eulaliopsis, Homozeugos, Pogonatherum and Lophopogon together 1956 Cytotaxonomy of the Andropogoneae. I. 275 with two other genera Trachypogon and Germainia. Bews also treated many of these as closely related to one another and far removed from the Saccharinae, however, Hubbard (1935) treats them together as Polliniastrae. Of the twenty-two genera listed most are rather small and four (Isch nochloa, Polliniopsis, Eulaliopsis, and Polytrias) are represented by only one species. Only three genera (Erianthus, Microstegiur, and Eulalia) have as many as twenty-five species. Most of the genera are restricted to tropical Asia but two (Homozeugos and Miscanthidium) are found only in Africa and one genus, Eriochrysis, is found in both tropical Africa and tropical America.

Key to the genera of the Saccharinae

AA. Racemes in more or less compound panicles on an elongated primary floral axis, spikelets one-flowered (two in Spodio pogon), lemma two-lobed with the awn from between the lobes, or awnless. (Saceharininae) A. Axis of the rachis continuous, or disarticulating tardily, spikelets falling free, all spikelets pedicellate. I. Racemes verticillate, lemma deeply lobed ...... Eccoilopus II. Racemes not verticillate, lemma not, or scarcely, lobed. 1. Spikelets awnless. a) Racemes in spike-like panicles, first glume somewhat delicate, stamens one or two ...... Imperata b) Racemes in open panicles, first glume hardened, stamens three ...... Sclerostachya 2. Panicles abundantly branched, spikelets usu ally awned. a) Rachis continuous, glumes membrane ous, spikelets in broad fan-shaped panicle, leaf midrib normal ...... Miscanthus b) Rachis disarticulating tardily, glumes tough, panicle a branched thyrse - form; leaf midrib much thickened Miscanthidium B. Axis of the rachis disarticulating, spikelets in pairs, one sessile, the other pedicellate. I. Spikelets awnless, panicles abundantly pilose. 1. Sessile spikelet male, pedicellate female..... Eriochrysis 2. Sessile spikelet fertile, pedicellate male or neuter. a) Glumes tough, panicles narrow, woolly haired ...... Narenga b) Glumes membraneous, panicles open, silky haired ...... Saccharum II. Spikelets awned (or first glume at least pointed); panicles usually not pilose. 1. Racemes long peduncled, few pairs of spike lets, two-flowered, lemma deeply cleft, weakly keeled ...... Spodiopogon 276 R. P. Celarier Cytologia 21

2. Racemes subsessile, several pairs of spikelets, one-flowered, lemma not cleft, first glume two-keeled with incurved edges ...... Erianthus BB. Racemes on short primary floral axes, digitate, fascicled or single; lemma notched, awned from the sinus, rarely shortly two lobed...... (Eulaliininae) A. First glume deeply furrowed with longitudinal groove. I. Racemes solitary, rachis flat, not disarticulating. .. Ischnochloa II. Racemes several, subdigitate, axis of the rachis disarticulating ...... Microstegium B. First glume more or less smooth on back. 1. First glume of the sessile spikelet with broad apex, pedicellate spikelets reduced to pedicels ...... Apocopis II. First glume of sessile spikelet with narrow apex. 1. Spikelets paired, both pedicellate. a) Lemma of the lower floret with a well developed geniculate awn from between the teeth; lemma of upper floret awned ...... Polliniopsis b) Lemma of lower floret stipiform, ex tremely narrow, entire; lemma of upper floret stipiform or narrow. Pseudopogonatherum 2. Spikelets otherwise a) Spikelets in threes, at each rachis joint, two sessile and one pedicellate. Polytrias b) Spikelets in pairs at each rachis joint, one sessile the other pedicellate. (1) Lemma scarcely two lobed, spikelets subterete, (a) Callus of spikelets very short and obtuse. Spikelets two-flowered. .... Eulaliopsis (b) Callus of spikelets long, pointed and pungent...... Homozeugos (2) Lemma deeply bilobed (bifid). (a) Racemes solitary, 2nd glume with long awn ...... Pogonatherum (b) Racemes two-many, 2nd glume unawn ed, or short awned. (1) Sessile spikelet fertile, one- flowered, stamens three. .. Eulalia (2) Sessile spikeletstwo-flowered, both staminate, stamens two. (a) Pedicellate spikelet with one male and one androgynous flower; racemes two-three, short, compact, rachis disarticulating. .. Lophopogon 1956 Cytotaxonomy of the Andropogoneae. I. 277

(b) Pedicellate spikelet with one androgyn ous flower, racemes two-many, digitate, rachis tough or scarcely disarticu lating...... Selerandrium Twelve of these genera have been studied cytologically and the results are recorded in Table 1. Imperata Cyrillo Although the genus has only a few species it is widespread throughout the tropics of the world. One species, I. arundinacea Cyrillo, has been studied cytologically. Bremer (1924), Janaki-Ammal (1941), Hubbard & Vaughan (1940) and. Tateoka (1954) all found 2n=20. Bremer (1924) found 10 bivalents at diakinesis and metapase I, with regular anaphase and telophase. Miscanthus Anderss. This is a small genus with only 8-10 known species and it is restricted to southeast Asia and the Pacific Islands. Although only three speices have been studied cytologically, five basic numbers have already been proposed. A detailed study of this genus is much needed, especially in view of the significant phylogenetic position that it is given by some workers (Avdulov, 1931). Hunter (1930) studied M. saccharifera Benth. and found that it had 64 somatic chromosomes. Avdulov (1928) studied another species, M. floridulus Warb., as EuZalia japonica Trin.1, and reported that it had a 2n number of 36. However, Bremer (1934) had recorded 2n=38 for this species, with 19 bivalents at metaphase I. M. sinensis Anderss. has been studied by four workers and different numbers have been reported. Hunter (1930) reported a somatic number of 42 and this same number had been previously reported by Church (1929) for the variety zebrinus. Moriya and Kondo (1950) studied the meiotic behavior of the variety gracillimus and found that it had a somatic complement of 28 with 14 bivalents at metaphase I. Recently Takeoka (1954) has reported still another number, 2n=40. In this work both M. sinensis and the variety zebrinus were available for study. The chromosomes were large in size and the somatic number of both was 38. Diakinesis and metaphase I were very satisfactory for analysis (Figs. 1, 2). Twenty cells were analyzed at these stages and in both varie ties only one cell was found without 19 bivalents. In both cases 2 univa lents and 18 bivalents were recorded. At anaphase and telophase I there were no irregularities observed in either variety, and the distribution of the chromo somes to the daughter cells was always 19:19 (Fig. 3). The second division was studied only in M. sinensis which was found to be completely normal. 278 R. P. Celarier Cytologia 21

In view of the great variation in the findings in the genus and especially in the species M. sinensis, it seems premature to draw any definite conclusions. Instead of settling matters this report makes it all the more obvious that a detailed cytotaxonomic study is much needed. It appears, at this stage, that several chromosomal factors may have been involved in the evolution of the species, or that more than one species is involved in this complex. Miscanthidiunt Stapf This is a rather small genus of tall marsh grasses. There are less than ten species, all restricted in distribution to tropical Africa. The cytology has not been studied in detail for any of the species, but Brett (1954) has reported 2n=28 for M. violaceum Schum. Saccharum L. This important genus composes probably 6-10 species, all restricted to tropical and sub-tropical habitats. Their origin is difficult to ascertain be cause they have been under cultivation, either as ornamentals or for their sugar content, since before recorded history. However, they appear to be Oriental in origin, probably arising in south east Asia. Cytologically they form an interesting group and have been subjected to numerous investigations. A brief summary of these results is given in Table 1. Two strikingly different cytological types are found in this genus. 1) Chromosome number constant, basic number ten, meiotic behavior fairly regular. This group includes S. officinarum. 2) Chromosome number variable, basic number not known, meiotic behavior often irregular. This group includes S. spontaneum L., S. robustum Jeswiet, and S. barberi Jeswiet. S. sinense Roxb. seems to be, as yet, too incompletely known to draw definite conclusions, but the available evidence suggests that it has variable chromosome numbers. Also of interest are the hybridization studies made with the genus. Successful intergeneric hybrids have been made with many other genera, some of which are rather widely separated from Saccharum. Hybrids have been reported with Sinocalamus, Bambusa, Zea, and Coix from outside the tribe (Janaki Animal, 1941, Parthasarathy, 1951; Venkatraman, 1937, Loh, et al. 1951), with Sorghum (Venkatraman and Thomas, 1932) from outside the subtribe and with Imperata, Miscanthus, Sclerostachya, Erianthus, Narenga and Miscanthidium from within the subtribe (Parthasarathy, 1948; Govindas wamy, 1948; Janaki Ammal, 1941; Loh, 1947; Brett, 1954; Barber, 1916; Rumke, 1934). This subject has been recently reviewed by Brett (1954) and Raghavan (1954). Erianthus Michx. with nine bivalents and two univalents. Fig. 9. Metaphase I in E. ravennae with nine bivalents and two univalents. Fig. 10. Diakinesis in E. munja with 30 bivalents (arrow indicated two overlapping bivalents). 1956 Cytotaxonomy of the Andropogone ae. I. 279

Figs. 1-10. Chromosome Behavior in the Saccharinae. 1350•~. Fig. 1. Diakinesis in Miscanthus sinensis with 19 bivalents. Fig. 2. Metaphase I in M. sinensis with 19 biva lents. Fig. 3. Telophase I in M. sinensis showing 19:19 distribution of chromosomes to daughter cells. Fig 4. Metaphase I in Erianthus alopecuroides with 30 bivalents (arrows indicate 2 bivalents overlapping) five of which are much larger than the others. Fig. 5. Diakinesis of Erianthus hostii with 10 bivalents. Fig. 6. Metaphase I of E. hostii with two configurations that suggest quadrivalents. Fig. 7. Telophase I in E. hostii with 10:10 distribution of the chromosomes to the daughter cells, Fig, 8. Diakinesis in E. ravennae 280 R. P. Celarier Cytologia 21

Table I. Cytology of Saccharinae 1956 Cytotaxonomy of the Andropogoneae. I. 281

Table I. Cytology of Saccharinae, Cont. 282 R. P. Celarier Cytologia 21

This is one of the largest genera of the subtribe and has the widest distribution. There are approximately 25-30 speceies, distributed throughout the tropical, sub-tropical and warm temperate regions of both hemispheres. It appears that they might will be separated into two sub-genera, one with two anthers and an American distribution, and the other with three anthers and an Old World distribution. 1. American species E. strictus Baldw. (not Bluff. et Fingerh.) was studied by Brown (1951) and found to have a diploid number of 30. Unfortunately no meiotic studies were made. E. alopecuroides Ell. was studied from material collected at Broken Bow, Oklahoma. It was found to have 2n=60 and regularly to have 30 bivalents at diakinesis and metaphase I (Fig. 4). There was considerable variation in the size of the chromosomes at metaphase I but there were 5 bivalents that were noticably larger than the others (Fig. 4). The few cells observed at anaphase and telophase in both the first and second divisions were com pletely normal. 2. Old World species E. hostii Griseb. was represented by two entries, both from Turkey. Both had 2n=20 with a predominance of ten bivalents at diakinesis and metaphase I (Fig. 5). However, cells were seen, in both entries, with two, and in one case four, univalents. Also there was an occasional cell that suggested quadrivalents (Fig. 6). However, anaphase and telophase I were always regular with 10:10 distribution of the chromosomes (Fig. 7) and no irregularities were seen in the second division. E. ravennae Beauv. was first studied by Bremer (1924) who reported 60 somatic chromosomes. Later Janaki-Ammal (1941) reported types with 2n= 20 as well as plants with a chromosome fragment plus the normal comple ment. In this study one entry was available and it was also found to have 2n=20. Although normally ten bivalents were seen at diakinesis, occasional ly two univalents were seen at diakinesis and frequently at metaphase I (Figs. 8, 9). Since anaphase and telophase were quite regular it seems likely that these univalents were the results of precocious separation of chiasmata. E. japonicus Beauv.1 was studied by Bremer (1925) and found to have1 In the process of reviewingthe manuscript of this report, Dr. E. R. Sohns,of the Smithsonian Institution Herbarium, brought to my attention a problem of synonymy involved here. This is, I feel, such a strong case for the need of voucher specimens that Dr. Sohns' comments are here included: "Chromosome numbers have been reported for Erianthus japonicus (Thunb.) Beauv. [2n=60], Eulalia japonica (Thunb.) Trin. [2n=36] and Miscanthus sinensis Anderss, [2n=42]. The first two names are synonyms of the third and the correct taxonomic citation is as follows: Miscanthus sinensis Anderss., "Of v. Svensk . Vet. Akad. Forh. 12: 166. 1856. China. [Saccharum japonicum Thunb., Linn. Soc. Trans. 2: 328. 1794. NOT Miseanthus japonicus Anderss. 1855.] 1956 Cytotaxonomy of the Andropogoneae. I. 283

60 somatic chromosomes with 30 bivalents at diakinesis. E. Sara (Roxb.) Rumke has been found by Rumke (1934) to have a somatic number of 60 with 30 bivalents at metaphase I. The following species have long been considered to belong to Saccharunt rather than to Erianthus by many workers and there is still no uniformity of opinion. However, since they have been shown by both cytological and morphogical studies to be related, and somewhat different from other Saccharunt species, they are treated here as belonging to Erianthus. E. arundinaceus (Retz.) Jeswiet has been studied by both Bremer (1924, 1934) and Janaki-Ammal (1941). Bremer found three entries, one from Indo china, one from Sumatra, and one from Celebes, to have a somatic number of 60, and in the one entry in which meiosis was studied 30 bivalents were found. Bremer also found 2n=40 type from Coimbatore, India and Janaki Ammal found a 2n=40 type which was apparently from India. E. munja (Roxb,) Jeswiet was first studied by Bremer (1924) and found to have 2n=60 with 30 bivalents at diakinesis and metaphase I. This number was confirmed by Singh (1934) who also reported a type with 2n= 20 with 10 bivalents. In this study one entry was analyzed and it was found to have 2n=60 with 30 bivalents at diakinesis (Fig. 10) but no studies could be made at metaphase or anaphase. Sclerostachya A. Camus This is a very small genus of tropical Asia with only three species. It is closely related to Saccharu?n and has only recently been separated from it. One species, S. fusca (Roxb.) A. Camus, was studied cytologically by Janaki-Ammal (1940) and two chromosome types were found. One had a somatic number of 48 and the other 96. Narenga (Hance) Bor This genus is closely related to Saccharunt and is known from two species, N. porphyrocoma (Hance) Bor. and N. fallax (Balansa) Bor, natives of eastern Asia. Bremer (1924) reported the somatic number of N. porphyrocoma to be 30 and this has been verified by Janaki-Ammal (1941); in both instances meiosis was regular with 30 bivalents. The meiotic behavior of two entries

[Erianthus japonicas (Thunb.) Beauv., Ess. Agrost. 14, 162, 1812.] [Eulalia japonica (Thunb.) Trin., Acad. St. Petersb. Mem. VI. Math. Phys. Nat. 2; 333. 1832.] The chromosome numbers of three genera are reported, but the taxonomic names used apply to one species. So far as is known, there are no voucher specimens preserved by the original investigators. Without voucher specimens no one will be certain what species were used in these studies. The actual chromosome count, the drawings and photographs of the various phases (if any) are accepted, but the identification of the material used is another matter. Properly annotated voucher specimens, the name (s) of which is given in the published account, should not only be cited in the published work, but they should be deposited in an accessible herbarium." 284 R. P. Celarier Cytologia 21

was studied by Moriya (1950). One was found to be completely regular with 15 bivalents at metaphase I but the other had considerable multivalent as sociations. In both cases, however, the chromosome distribution to the daughter cells was predominately 15:15. Eccoilopus Steudel. There are some 8-10 species in this genus, found only in tropical and subtropical east Asia. E. cotulifer (Thunb.) A. Camus was supplied by A. Moriya from Utsu nomiya, Japan. It was found to have a somatic number of 40 with 20 bivalents at diakinesis and metaphase I (Fig. 11) and to be regular throughout. Spodiopogon Trin. This is a genus of moderate size, closely allied to Eccoilopus, with pro bably more than 20 species found principally in China and Japan. One species, S. sibiricus Trin., was studied and found to have 2n=40. More than 50% of the cells had quadrivalents (Figs. 12, 13), usually one but occasionally two. Other than quadrivalents only bivalents were seen and the average per cell was 18.5 II and 0.8 IV. Anaphase and telophase I were regular (Fig. 14) in behavior, but with an occasional 21:19 distribution to the daughter cells. The second division was regular. Pogonatheruyn Beauv. This is a genus with only a few species restricted to tropical east Asia and some of the Pacific Islands. P. paniceum (Lam.) Hack. has been reported by Hubbard and Vaughan (1940) and Janaki-Ammal (1945) to have a diploid number of 20 Eulalia Kunth The taxonomic status of this genus is still unsettled but for this study the separation of the complex made by Camus (1921) will be followed. In this separation the complex was divided into Eulalia, Microstegium and Pseudopogonatheruna A. Camus. Even in this restricted sense Eulalia is a good sized genus with some 30 described species. It is most abundant in tropical Asia, but is also well represented in Africa. E. geniculata Stapf was supplied for this study from seed collected at Nairobi, Kenya. It was found to have a somatic chromosome number of 20 and there were always 10 bivalents at diakinesis and metaphase I (Fig. 17) and 10:10 distribution to the daughter cells (Fig. 18). No irregularities were observed at any stage. Microstegium Nees This is similar in size and distribution to Eulalia except that it has fewer representatives in Africa M. nudum (Trin.) A. Camus was found to have a 2n number of 20; all cells observed had 10 bivalents at diakinesis and metaphase I, and were 1956 Cytotaxonomy of the Andropogonea e. I. 285

Figs. 11-19. Chromosome behavior in the Saccharinae 1350•~. 11. Diakinesis in Ec coilopus cotulifer with 20 large bivalents. 12. Diakinesis in Spodiopogon sibiricus showing a quadrivalent (only part of the cell included). 13. Diakinesis in S. sibiricus with 18 bivalents and one quadrivalent (notice the difference in cell and chromosome size as compared with Eccoilopus). 14. Telophase I in S. sibiricus with 20:20 distribution of the chromosomes. 15. Metaphase I in Microstegium ciliatum with 20 bivalents. 16.

Telophase I in M. ciliatum with 20:20 distribution of the chromosomes. 17. Metaphase

I of Eulalia geniculata with 10 bivalents. 18. Telophase I of E. geniculata with 20:20 distribution of the chromosomes. 19. Telophase I in Microstegium nudum with 10:10

distribution of the chromosomes. 286 R. P. Celarier Cytologia 21 completely regular at anaphase and telophase I (Fig. 19). Takeoka (1954) has also found 2n=20 for this species.M. ciliatum (Trin.) Camus was studied from materials collected at Kunigami, Japan. This species was found to have a 2n number of 40 with 20 II at metaphase I (Fig. 15) and with normal anaphase and telophase I (Fig. 16). M. vimineum (Trin.) A. Camus was studied by Avdulov (1928) who reported 2n=40.

Discussion and conclusions As mentioned earlier, all members of the Andropogoneae are extremely far advanced in regard to floral characters. However, within the tribe there are various degrees of specialization along several general lines. Within the two subtribes studied here, both show several primitive characters in relation to the other subtribes; and it is only with difficulty that degrees of primiti veness can be established. The subtribe Dinaeriinae C. E. Hubb. is, however, rather divorced from the remainder of the Andropogoneae and is consequently not considered as representing a direct line of evolutionary development. It seems more likely that it differentiated very early. The Saccharinae Kunth and the Ischaeminae Stapf are, on the other hand, obviously closely related. From floral character alone it is difficult to decide which of these subtribes is the more primitive. However, the binate or solitary racemes of the Ischaeminae and the several modifications of the joints and pedicels suggest that it may be somewhat more advanced than the Sac charinae. Also it has been pointed out by Bews (1929) that the Saccharinae (especially the Saccharininae Pilger) are mostly hygrophilous, tallgrowing forms, found in warmer regions and therefore to be considered ecologically more primitive than the Ischaeminae. Of the two groups within the Saccharinae there seems to be little doubt but that the Eulaliininae Pilger is the more advanced. Not only are the spikelets arranged in digitate, or in some cases solitary, racemes, but several annual species are found here and, according to Bews (1929), they are more advanced ecologically being, on the whole, smaller plants adapted to drier conditions. Several evolutionary trends in morphological characters found in this subtribe seem to be rather important in the Andropogoneae. The most primitive members of the subtribe are apparently those with numerous multi jointed racemes in open panicles, binate spikelets both of which are pedi cellate, and a continuous rachis. Included here are the genera Eccoilopus and Miscanthus. It seems likely that Imperata, with its spike-like panicles and stamens reduced to one or two, was separated early and that very little has developed from it. Miscanthidium Stapf was probably derived from Mis- 1956 Cytotaxonomy of the Andropogoneae . I. 287 canthus and seems to have contributed little to the phylogeny of the tribe. Sclerostachya (Anderss.) E. G. and A. Camus which occasionally has a female floret in the long pedicellate spikelets, may well be the progenitor of the heteromorphous spikelets in which the pedicellate spikelets are female as in Eriochrysis Beauv., Lophopogon Hack., and Scleandrium Stapf and Hubb. (also Trachypogon Nees in the subtribe Andropogoninae Stapf). Eccoilopus and Spodiopogon Trin. are obviously closely related and although Spodiopogon is more primitive in being two flowered, it is more advanced in almost all other characters. Thus it seems that Eccoilopus and Miscanthus are the most primitive genera of the Andropogoneae and very likely they, or closely related forms, are ancestral to Erianthus, Saccharum, Narenga, and probably Sclerostachya. However, the relationship with the Eulaliininae is not so obvious. Moreover, both Eccoilopus and Miscanthus have medium sized chromo somes (ca. 4 microns at diakinesis) as do Erianthus, Saccharumn, and Na renga. The chromosomes of Miscanthus are somewhat larger than the others. The chromosomes of Eccoilopus are considerably larger than those of Spodiopogon, and the chromosomes of the latter approach the size of those in the Eulaliininae, especially in Eulalia (ca. 3 microns). The three genera of the Eulaliininae that have been studied cytologically are closely related and, of the three, Eulalia seems to be the most primitive. Pogonatherum is much advanced with solitary racemes, and Microstegium species are ordinarily annuals. The chromosomes of all these genera are small but they are considerably larger in Eulalia. Polyploidy is highly developed in the Saccharinae. Every genus where more than one species has been studied has demonstrated polyploidy. From the studies of chromosome behavior at meiosis all cases appear to be genomic allopolyploids or segmental allopolyploids. There are, however, several in stances of intraspecific polyploidy, principally in the genus Erianthus, and it is difficult to reconcide allopolyploidy with this morphological stability. The establishment of the basic number (or numbers) for the Andro pogoneae is a somewhat complicated affair, principally because of the small number of genera and species that have been adequately studied, and the high degree of polyploidy found. Five has been suggested as the basic number for the tribe (Garber, 1944; 1950; Celarier, 1956), but much of the evidence for this is of a secondary nature. Ten (or five) and nine are generally accepted by most workers (Avdulov, 1931; Darlington and Janaki-Ammal, 1945; Harlan, 1956). Of the more primitive genera, Eccoilopus has a basic number of five or ten, but at least four numbers are suggested for Nliscanthus. Seven was proposed by Moriya and Kondo (1950) from their study of M. sinensis and this is not inconsistent with the data of Church (1929) and Hunter (1930) on the same species. Eight is suggested by the 2n=64 found in M. Cytologia21, 1956 20 288 R. P. Celarier Cytologia 21 saccharifera (Hunter 1930); nine was advanced by Avdulov (1928, 1931) from his report of 2n=36 for M. floridulus; and ten, or five, is seen in Takeoka's (1954) report of 2n=40 for M. sinensis. However, for all species that have been studied by more than one worker, there has been disagree ment. Bremer (1934) reported 2n=38 for M. floridulus which is the same number reported for M. sinensis in this study. Sclerostachya with 2n=48 and 2n=96 was concluded by Janaki-Ammal (1940) to represent a basic number of six. Erianthus and Narenga both indicate a basic number of five (Celarier, 1956) and the closely related Saccharum has five or ten (or possibly six in certain types of S. spontareum). Spodiopogon has a basic number of ten, or five, as do all members of the Eulaliininae that have been studied. It cannot be overemphasized that only a few genera of the Saccharinae (12 of 22) have been studied cytologically, and in these only a few species have been examined cytologically. The conclusions that are drawn from the evidence at hand are therefore only tentative proposals. The following diagram gives an outline of the suggested evolutionary pattern of the subtribe: 1956 Cytotaxonomy of the Andropogoneae . I. 289

Summary

1. The cytology of the subtribe Saccharinae , including chromosome numbers and meiotic behavior, is reviewed . 2. Chromosome numbers and behavior are reported for the first time for three genera, Eccoilopus, 5podiopogon , and Eulalia. 3. Twelve genera and twenty-eight species of the subtribe have now been studied cytologically. 4. Polyploidy is shown to occur in all genera in which more than one species has been studied. 5. Several different basic numbers are indicated but five (or ten) is by far the most frequently reported. 6. All chromosomes in the subtribe are small , but some are much smaller than others and there seems to be a phylogenetic trend from the larger to the smaller. 7. Some of the general morphological differences in the subtribe are discussed, especially in relationship to phylogeny. 8. An attempt is made, by combining morphological and cytological data, to diagram a likely path of evolution for the subtribe.

Literature cited

Avdulov, N. P. 1928. Systematic karyology of the family Gramineae. Proc. All-Russ. Botanists Congress. pp. 65-97. - 1931. Karyo-systematische Untersuchung der Familie Gramineen. Bull. Appl. Bot., Genet., and PI. Breeding. Suppl. 43. Barber, C. A. 1916. Studies of Indian sugar canes II. Mem. Dept. Agric. India , Bot. 8: 103-199. Bews, J. W. 1929. The World's Grasses. London. Blake, S. T. 1944. Monographic studies in the Australian Andropogoneae I. Univ. of Queensland Papers. Dept. of Biology 2: 1-62. Blatter, E. and McCann, C. 1935. The Bombay grasses. Delhi. Bor, N. L. 1940. Flora of Assam. vol. 5. Calcutta. Bremer, G. 1925. The cytology of the sugarcane III. Genetica VII: 293-322. (translation of the 1924 Datch paper). - 1934. De Cytologic van bet Suikerriet VII. Arch. Suik. Ned. 42: 141-166. Brett, P. G. C. 1954. Saccharum-Miscavethidium hybrids. Jour. of Genet. 52: 542-546. Brown, W. V. 1951. Chromosome numbers of some Texas grasses. Bull. Torrey Bot. Club. 78: 292-299. Camus, A. 1921. Notes sur quelques genres de Graminees. Ann. de la Soc. Linn. de Lyon LXVII1: 197-208. Camus, E. G. and Camus, A. 1922. Gramineae in Le Comte, H. Flore General de l'Indo- Chine. Vol. 7. Paris. Celarier, R. P. 1956. Additional evidence for five as a basic number of the Andropogoneae (Rhodora. 58: 135-143). Church, G. L. 1929. Meiotic phenomena in certain Gramineae 11. Paniceae and Andropo goneae. Bot. Gaz. 88: 63-84. Darlington, C. D. and Janaki-Ammal, E. K. 1945. Chromosome Atlas of Cultivated Plants. London

20* 290 R. P. Celarier Cytologia 21

Garber, E. D. 1944. A cytological study of the genus Sorghum, subsections Para-Sorghum

and Eu-Sorghum. Amer. Nat. 78: 89-93.

- 1950a . Cytotaxonomic studies in the genus Sorghum. Univ. of Calif. Publ. in Botany

23: 283-361.

- 1950b . Cytotaxonomic studies in the genus Sorghum III. Bot. Gaz. 115: 336-342.

Gould, F. W. 1953. A cytotaxonomic study of the genus Andropogon. Amer. Jour. Bot.

40: 297-306.

Govindaswamy, S. 1948. M. Sc. Thesis. Madras Univ. (taken from Raghavan, T. S., 1954).

Hackel, E. 1889. Andropogoneae in De Candolle, A. Monographiae Phanerogamarurn VI. Paris.

Harlan, J. R. 1956. Theory and dynamics of grassland agriculture. (Princeton, New Jersey).

Hartley, W, 1950. The global distribution of tribes of the Gramineae in relation to historical

and environmental factors. Aust. Jour. Agr. Res. L: 355-373.

Hegi, G. 1936. Illustrierte Flora von Mittel-Europa . Munich.

Henrard, J. T. 1940. Notes on the nomenclature of some grasses . Blumea 3: 411-480.

Hitchcock, A. S. 1951. Manual of the grasses of the United States (revised by A . Chase) Washington, D. C.

Hooker, J. D. 1897. Flora of British India . vol. 7. London.

Hubbard, C. E. 1934. Gramineae Australiensis II . Kew Bull. 54: 444-451. - and Stapf , O. 1935. Sclerandrium truncatiglume. In Hook. Ic. Tabula 3262. 7 pp. - and Vaughan , R. E. 1940. Grasses of Mauritius and Rodriques. London.

Hunter, A. W. S. 1930. A karyosystematic investigation in the Gramineae. Canad . Jour. Res. (C) 11: 213-241.

Janaki-Ammal, E. K. 1940. Chromosome numbers in Sclerostachyafusca. Nature 145: 465. - 1941 . Intergeneric hybrids of Saccharum I, II, and III. Jour. of Genet . 41: 217-253. Keng, Y. L. 1939. The gross morphology of Andropogoneae . Sinensis 10: 274-343. Komarov, V. L. 1934-45. Flora Unionis Rerumpublicarum Sovieticarum Socialisticarum , Moscow.

Kuwada, Y. 1915. Uber die Chromosomenzahl von Zea mays L . Bot. Mag. Tokyo 29: 83-89.

Loh, C. S. 1947. Saccharum •~ Miscanthus hybrids . Jour. Sugar Cane Res. 1: 1-9. - Hu , T. H., Ma, P. T. and Tseng, P. M. 1951. A report on Saccharum •~ bamboo hybrids. Jour. Sugar Cane Res. 5: 13-33.

Mangelsdorf, P. C. and Reeves, R. G . 1939. The origin of Indian corn and its relatives, Texas Agric. Exp. Sta. Bull. 574.

Moriya, A. 1940. List of the chromosome numbers in the genus Saccharum and related

genera. Jap. Jour. of Genet. 16: 126-136. - 1950 . Contributions to the cytology of the genus Saccharum IV . Studies of chromo somes in wild Saccharum species in Formosa. Cytologia 15: 237-254 . - and Kondo , A. 1950. Cytological studies of forage plants I. Grasses . Jap. Jour. Genet. 25: 126-131.

Parthasarathy, N . 1948. Origin of noble sugarcane (Saccharum officinarium L .) Nature 161: 608. - 1951 . Chromosome elimination in Saccharum . Nature 168: 383-384.

Pilger, R. 1940. Gramineae, III: Unterfam . Panicoideae in Engler U. Prantl, Die Natur

lichen Pflanzenfamilien. vol . 2. Leipzig. - 1954 . Das System der Gramineae . (prepared for publication by E. Potztal) Bot. Jahrb. 76(3): 281-384.

Post, C. E. 1933. Flora of Syria , Palestine, and Sinai. Beirut. Raghavan, T. S, 1954. Cytogenetics in relation to sugarcane breeding . Cytologia 19: 133- 143.

Randolph, L. F. 1955 . History and origin of corn II. Cytogenetic aspects of the origin

and evolutionary history of corn . pp. 16-61 in Sprague, G. F. Corn and corn

improvement. New York . 1956 Cytotaxonomy of the Andropogoneae. 1. 291

Reeves, R. G, and Mangelsdorf, P. C. 1942. A proposed taxonomic change in the tribe Maydeae. Amer. Jour. Bot. 29: 815-817. Rhind, D. 1945. The grasses of Burma. Calcutta. Rumke, C. L. 1934. Saccharum-Erianthus bastaarden. Arch. Suikerind. Ned.-Ind. 211-263. Singh, T. S. N. 1934. Chromosome numbers in the genus Saccharurn and its hybrids. Indian J. Agr. Sci. 4: 290-92. Stapf. O. 1919. Gramineae in Prain. D., Flora of Tropical Africa. vol. 9. London. Tateoka, T. 1954, Karyotaxonomy in Poaceae II. Somatic chromosomes of some species. Cytologia 19: 317-328. Trimen, H. 1900. Handbook of the Flora of Ceylon. London. Venkatraman, T. S. 1937. Sugarcane-bamboo hybrids. Indian J. Agr. Sci. 7: 513-514. - and Thomas , R. 1932. Sugarcane-sorghum hybrids. General outline and early charac ters. Ind. J. Agr. Sci. 2: 19-27.