Ana Pproach to the Study of Grasses, the “Tribal Triangle”

LLANOS-A NEGLECTED GRAZING RESOURCE 17

(there are few good roads, no rail- uality, his philosophy of accepting towns. Should these hurdles ulti- ways, and even the Orinoco was what comes and making the best of mately be surmounted, cattle rais- not a good highway until recently it, and his lack of progressiveness. ing on the Llanos might become a dredged to Puerto Ordaz); (6) the What improvement in the situa- business enterprise rather than just inferiority of native grass pastures tion is possible? The cattle industry a way of life. and the difficulties encountered in could be made more productive and planting such introduced grasses as profitable by: (1) improving pas- LITERATURE CITED Guinea, Para, Napier, Guatemala tures (difficult and costly but not AUBREVILLE, A. 1949. Anciennetb de la and Natal, which can be grown only impossible) ; (2) supplying nitrogen destruction de la couverture fores- t&e primitive de 1’Afrique tropicale. on fertile, well-watered soils of and other essential minerals to the Bull. Agricole du Congo Belge small valleys ; (7) governmental soils; (3) introducing more fencing; 40(2) : 1347-1352. interference and civil strife; (8) (4) installing more windmills; (5) BENNETT, H. H. et al. 1942. Land conditions in Venezuela and their rela- the un-scientific methods of han- reducing fires, particularly in the tions to agriculture and human wel- dling the range and cattle with Eastern Llanos ; (6) growing feed fare. Soil Conservation Mission to consequent unsatisfactory results; crops adapted to local conditions Venezuela, U. S. Soil Conservation Service, Washington, D. C. (9) the uncontrolled fires which for fattening the range animals; (7) MYERS, J. G. 1933. Notes on the vegeta- annually destroy the better soils building more and better highways tion of the Venezuelan Llanos. Jour. and vegetation, fences and houses; into the Llanos; (8) improving the Ecology 21: 335-349. ----. 1936. Savannah and forest vegeta- (10) the difficulty of securing credit quality of the livestock and giving t>ion of the Interior Guiana Plateau. on livestock; (11) the antiquated the animals better care; (9) con- Jour. Ecology 24 : 162-184. methods of handling meat; and (12) structing more slaughter houses in SCHIMPER, A. F. W. 1903. Plant geog- raphy upon a physiological basis. the llanero himself-his individ- the vicinity of strategically located Oxford. 839 pp.

AnA pproach to the Study of grasses, the (tribes, genera, and species); and (3) the knowledge of the distribu- “Tribal Triangle” tion, habitat preference and economic importance of the major FRANK W. GOULD range grasses. Associate Professor, Department of n”(_;ngeand I orestry, A. k This paper is concerned primarily M. C allege of Texas, C allege Station, Texas with the second phase, specifically,

GROSTOLOGY, the science of The Gramineae not only is one of the taxonomic relationships of the A grass classification, is an essen- the largest of the families of flower- subfamilies and tribes. According tial prerequisite to the study and ing plants, but it also is one of the to the system of the great American practice of range management. Of most highly specialized in floral agrostologist, Dr. A. S. Hitchcock, prime importance to the range man- characteristics. The familiar grass the genera of grasses are grouped ager is a basic understanding of the spikelet is a greatly reduced and into 14 tribes. Ten of these tribes kinds, characteristics and qualities of contracted flowering branch bearing are placed in the subfamily Festu- important range grasses. For proper minute, reduced flowers protected coideae and four in the subfamily assimilation and retention of in- by scale-like floral bracts. The Panicoideae. The tribes are com- forrriation about grasses, it is ad- nature of the spikelet and of its prised of morphologically similar visable that the range manager parts, and the arrangement of the and supposedly closely related gen- undertake more of a study of agros- spikelets in the inflorescence are era. Due to lack of knowledge of oology than the mere memorization the principal bases for classification actual relationships, and because tf names and recognition of speci- of grasses. continuous evolutionary processes mens. He should become well ac- As a systematic science, the study have produced grasses that do not quainted with the basic framework of range agrostology includes three fit nicely into any taxonomic niche, of grass classification and should phases: (1) the recognition of vege- the placement of some genera in one obtain satisfactory concepts of tative and reproductive structural or another tribe is controversial. Dr. tribes, genera and species, and the units; (2) the learning of names and Hitchcock realized that his system interrelationships of these groups. characteristics of the important taxa was not entirely natural nor com- 18 FRANK W. GOULD

pletely satisfactory. In the publica- “primitive” tribes, namely the tain groups of the tribe Festuceae. tion “Genera of Grasses of the Bambuseae, Festuceae, and Ave- The Zoysieae is a highly “artificial” United States”, Hitchcock (1935) neae. The distinguishing features of tribe of tropical and subtropical noted, these tribes are : grasses whose affinities are mainly Bamboo tribe, BAMBUSEAE. Culms with the Chlorideae and the Festu- “Most of the genera of grasses fall woody; plants not flowering ceae. The concept of the Zoysieae naturally into one of the two series and fruiting annually. as herein treated is based on the of subfamilies. The remaining few are rather arbitrarily assigned to one or Oat tribe, AVENEAE. Culms not genus Hilaria. The distinguishing the other series. In the same manner, woody; plants flowering annu- features of the three tribes of Areas most of the genera may assemble into ally ; glumes exceeding the 2a and 2b are : distinct and well-marked tribes, lowermost floret ; lemmas Curlymesquite tribe, ZOYSIEAE. but several are not closely allied to awned dorsally. Infloresence a terminal bilateral the other genera in the tribe to which they are assigned but are so placed Fescue tribe, FESTUCEAE. Culms spike or spicate raceme; spike- for convenience in classification.” not woody; plants flowering lets disarticulating in clusters

The “Tribal Triangle” (Figure 1) has been developed to show relationships between the grass tribes of Hitchcock, and to mini- mize the memorization of series of characters in learning the tribes. Two sides of the Tribal Triangle, the lines separating Area 1 from Area 3 and Area 3 from Areas 2a, 2b and 4b, are based on the major lines of evolution in the grass. family: (1) the reduction in the spikelet from several perfect florets to one. (2) the modification of the inflorescence from a panicle to a spike or a series of spicate branches. The third side of the triangle repre- sents the principal difference between the subfamilies: the reduction FIG. 1. The Tribal Triangle. in the spikelet of the Panicoideae to a single perfect floret with a single annually ; glumes not exceeding from the continuous inflores- reduced (staminate or sterile) floret the lowermost floret or if so the cence axis. below it. The placement of tribes on lemmas not awned dorsally. Barley tribe, HORDEAE. Inflores- the division lines between areas in- In Areas 2a and 2b are those cence a terminal bilateral spike dicates the occurrence of grasses grasses of the Subfamily Festu- or spicate raceme; spikelets in these tribes with the character- coideae in which the inflorescence falling separately or with joints istics of both areas. has been reduced to spike, spicate of a disarticulating inflores- Needless to say, although the raceme or a series of spicate cence axis. . majority of our range grasses fit branches. As this type of evolution- Grama tribe, CHLORIDEAE. In- well into this scheme, there are ary reduction apparently has taken florescence of two or more exceptions such as tall oatgrass place independently in a number of (occasionally one) lateral, uni- (Arrhenatherum elatius), in which relatively unrelated groups, the lateral spicate branches. the spikelets are 2-flowered with a tribes in this area are not altogether In Area 3 are those grasses of the perfect floret above and a staminate natural, that is, they probably are subfamily Festucoideae with panic- floret below. comprised of both closely related ulate inflorescences and with a In Area 1 of the Tribal Triangle and distantly related genera. single fertile floret per spikelet. With are grouped the most unspecialized Grasses of the tribes Chlorideae and the exception of the small tribe and thus hypothetically the most Hordeae are interrelated with cer- Phalarideae, the spikelets of these GRASSES : THE TRIBAL TRIANGLE 19

grasses do not have reduced florets has close affinities with the Andro- attempt is made to completely sum- above or below the fertile one. The pogoneae. Grasses of the subfamily marize the characteristics of these four tribes of Area 3 may be dis- Panicoideae are remarkably uniform groups as they are treated thor- tinguished as follows : in the principal spikelet character- oughly and adequately by Agnes Canarygrass tribe, PHALARIDEAE. that of the single perfect floret with Chase in her excellent introductory Reduced florets (staminate or a single sterile or staminate floret grass study “First Book of Grasses” sterile) present below the per- below. The distinguishing features (1922), and by A. S. Hitchcock in fect one. of the tribes in Areas 4a and 4b are : the Manual of Grasses of the Time thy tribe, AGROSTIDEAE.Re- Millet tribe, PANICEAE. Glumes United States (1951). The Tribal duced florets not present below thinner and less firm than the Triangle follows Hitchcock’s classi- the perfect one; spikelets bi- fertile lemma. fication system and is based on sexual ; glume well developed. Bluestem tribe, ANDROPOGONEAE. morphological characteristics and Rice tribe, ORYZEAE. Reduced Glumes thicker and firmer lines of morphological evolution. florets not present below the than the fertile lemma; spike- Structural characters, although not perfect one ; spikelets bisexual ; lets usually in pairs of one always reliable indicators of genet- glumes reduced. perfect and one staminate or ical relationships, provide the best Indian rice tribe, ZIZANIEAE. sterile. practical basis for grass classifica- Reduced florets not present Corn tribe, TRIPSACEAE. Glumes tion. below the perfect one; spike- thicker and firmer than the LITERATURE CITED lets unisexual ; glumes absent. fertile lemma; male and female The two principal tribes of Areas spikelets on separate parts of CHASE, AGNES. 1922. First book of grasses. MacMillan Co., N. Y. 121 pp. 4a and 4b, the Paniceae and the the inflorescence or plant. HITCHCOCK, A. S. 1936. The genera of Andropogoneae, are relatively Molassesgrass tribe, MELINIDEAE. grasses of the United States with “good” tribes, both in respect to Glumes and fertile lemma about special reference to the economic species. U. S. Dept. Agr. Bull. 772. morphological characteristics and equal in thickness and firmness. 302. pp. genetical relationships. The small The Tribal Triangle is presented . 1951. Manual of the grasses of’the United States. U. S. Dept: Agr. Misc. tribe Tripsaceae, well known for its as an aid to the learning of critical Publ. 200.1051 pp. (2nd ed., revised cultivated maize or corn, Zea mays, subfamily and tribal characters. No by Agnes Chase)

FIRST KODACHROME SLIDE CONTEST

Eighth Annual Meeting of the American Society of Range Management

San Jose, California, January &X&3, 1956

Society members are invited to enter Kodachrome slides they will be displayed for competition, with awards for the that they have taken in two classes: three slides placed highest in each class and the top slide of 1. Range condition class the display. 2. Wildlife of the range Rnles of the photograph contest shall prevail with regard Kodachrome slides may be 2 x 2, or larger, mounted or un- to typed description, contestant’s name and address, and his mounted. Contestants may enter one slide in each class. responsibility to take the slides to and from the display booth. Slides will be projected at an evening session. Thereafter, -Les Alhee, Chairman, Slide Contest