Proc. Indian Acad. Sci. (Plant Sei.), Vol. 96, No. 2, June 1986, pp. 113-120. Printed in India. Contribution to the leaf anatomy of the genus Pennisetum Rich M SURYANARAYANA RAJU, V SESHAVATHARAM and S APPA RAO* Department of Botany, Andhra University, Waltair 530 003, India *Genetic Resources Unit, International Crops Research Institute for the Semi-Arid Tropics, Patancheru 502 324, India MS received 21 December 1985; revised 1 May 1986 Abstraet. Leaf epidermal patterns in 18 species belonging to the genus Pennisetum Rieh., were described. The va¡ in the leaf epidermal characters was utilized for the identification of species. Macro hairs were reeorded only in Pennisetum americanum, Pennisetum clandestinum, Pennisetum polystachyon, Pennisetum pedicellatum, Pennisetum villosum, Pennisetum cenchroides, Pennisetum purpureum• typhoides 0aybrid) and Pennisetum orientale. Short cells between the veins were paired, solitary or more than two celled. Prickle hairs were absent only in Pennisetum polystachyon. Hooks were absent ordy in Pennisetum hohenackeri and Pennisetum squammulatum. Stomata with triangular subsidiary cells occur in all the species. Silica bodies are of various types. A dichotomous key was prepared based on epidermal characters for the identification of the different species studied. Keyworfls. Pennisetum; Gramineae; epidermis. 1. Introduction Leaf epidermal morphology is now considered as one of the most important tools in understanding the phylogeny and interrelationships of various families of angiosperms. The epidermal patterns attained a high degree of specialization and differentiation in the family Gramineae. As early as in 1932-1936 Prat utilized these characters in the classification of the grasses and believed that these characters were reflecting their true relationships more exactly than spikelet characters. Several subsequent workers studied the epidermis in the Gramineae. Metcalfe (1960) in his monumental work described in detail the leaf anatomy of 206 genera and 413 species. The present study aims at the leaf epidermal morphology of 18 species belonging to the genus Pennisetum. 2. Materials and methods Al1 species of the genus Pennisetum Rich., except P. hohenackeri were collected from the plants growing at ICRISAT, Hyderabad. P. hohenackeri was collected from Araku, Andhra Pradesh. A fully matured leaf (4th from the base) was collected in each case. The portion of the blade examined was about 9 cm from the sheath. The peelings were made by scraping the epidermis with a sharp blade following the method described by Metcalfe (1960). The preparations were stained with aqueous Safranin and were mounted in glycerol. In some cases, the method described by Mohan Ram and Vijayalaxmi Nayyar (1974) gave good results. 113 114 M Suryanarayana Raju, V Seshavatharam and S Appa Rao 3. Results The epidermal patterns of both the abaxial and adaxial surfaces were studied giving emphasis to the nature of long and short cells, silica bodies, macro and micro hairs, prickle hairs, nature and dist¡ of stomata and interstomatal cells and papillae. The data has been summarised in table 1. 3.1 Macro hairs Among 18 species investigated, macro hairs were recorded in P. polystachyon, P. americanum, P. clandestinum and P. pedicellatum on both the surfaces, and only on the adaxial surface in P. villosum, P. cenchroides, P. purpureum x typhoides (hybrid) and P. orientale. They are absent in the rest of the species investigated. 3.2 Micro hairs Two-celled micro hairs are uniformly of the Panicoid type and occur in all the species studied, with a thick walled basal ceU anda hyaline thin walled distal ceU. 3.3 Long cells Long cells are thin walled in P. pedicellatum, P. villosum, P. cenchroides, P. mezianum, P. ciliaris and P. divisum and thick waUed in the rest of the species investigated. The walls of the long cells are sinuous in the species except in P. purpureum. The walls are pitted in P. polystachyon, P. americanum, P. clandestinum, P. purpureum x typhoides (hybrid), P. purpureum, P. macrorum, P. hohenackeri, P. setaceum and P. squammulatum and ate non-pitted in the rest. Their size ranged from 98-6 x 28.0 la in P. macrorum to 238.5 x 40.8 q in P. americanum (table 2). 3.4 Short cells On the abaxial surface, short cells over the veins ate in continuous rows of less than 10 cells in P. cenchroides, P. purFureum, P. macrostachium, P. ciliaris and P. divisum while in the rest they occur in long rows of more than 20 cells each. Short cells are absent on the intercostal region in P. pedicellatum and P. ciliaris; occur in rows of 3 cells in P. divisum; solitary in 1". polystachyon, P. clandestinum, P. purpureum x typhoides (hybfid), P. orientale, P. orientale x typhoides (hybrid), P. raacrorum and are paired in the rest of the species. On the adaxial surface short cells on the costal region are in short rows of less than 10 cells in all the species. Short cells between the veins are absent in P. clandestinum, P. pedicellatum, P. macrorum, P. mezianum and P. ciliaris; occur in 3 celled rows in P. divisum; solitary in P. purpureum x typhoides (hybrid), P. orientale x typhoides (hybrid) and paired in the rest. In size they range from 66-2 x 6.5 la in P.pedicellatum to 20.8 x 6.5 ~t in P. orienta& x typhoides (hybrid)o Table 1. Epidermal patterns in 18 speci'es of the genus Pennisetum. Macro Prickle hairs hairs Hooks Long cell size Short cell size Interstomatal cell Name of the species Ab Ad Ab Ad Ab Ad (q (p) size Of) P. polystachyon + + + + 167.04. 19"3 x 34"54.2-1 30.64.2-7x 6.84.0.0 121-34. ll.9x 36.24.2.3 P. americanum + + - + + + 238.5 4. 27.8 x 40.8 4.1-8 37.94.4-9x10.2• 164-94. 15-I x 48.64. 2-3 P. clandestinum + + - + + + 191.3 4. 34.2 x 39.8 4. 2.3 39.24.1.6x!0.24.0.0 60.7-4- 23.9 x 48.5 4. 1.5 P. pedicellatum + + - + + - 230"4+33'0• ~.24.1.6x 6.54.0.0 151.44-46.5 x 51.3 + 1.9 P. villosum - + - + + + 190.34.23-0 x 37"94.5"5 33.24.3.2• 6.54.0-0 119.44. 18.3 x 41-5 4.9.2 P. cenchroides - + + + + + 177"9 4. 19.4 x 36.5 4. 5.3 33.34.0-7x 6.54.0.0 93.5 4. 18.5 x 34.0 4. 2.6 P. purpureum x typhoides - + - + + + 102-94.25"0• 35.74.1.7x10.24.0.0 55.44. 10-8 x 35.54. I-6 (hybrid) P. orientale - + - + - + 170"2+40"2• 33-24.3.2x 6.54.0.0 96.5+ 14.5 x 31.84.2.3 P. purpureum + + + + 106"8 4.16"7 • 40"44- 2"5 22.9• 53-24- 6.9 x 51.04.3.9 P. macrostachium + + + + 187"04. 21"8 x 41"84-1"5 33.04.1.5• 77.64- 3.6 x 52.24. !-6 P. orientalextyphoides + + + 173"44. 25"7 x 39"9+ 2.2 ~.84.2-9• 6.54.0.0 89.3 4. 39.6 x 45.0 + 4.7 (hybrid) P. macrorum + + + 98.64.11-6 x 28"04. 2.5 26-5• 6-54.0.0 56.84. 19.3 • 28.44-3-7 P. hohenackeri + 118"7 4. 37"5 • 41"2 4. 1"6 45.34.2.0• 6.54.0.0 76.04. 16.6 • 40.24- 3.9 P. setaceum + + + + 160"84.44"5 x 31"84.4-1 32.34.1.7x 6.54.0.0 119.54.58-6• P. mezianum + + + + 206"24-37"6• 36'44.2"3 31-54.3.2• 183.24. 30.6 x 34.44-3.2 P. ciliaris + + + + 185-74.18"1 • 39.94.4.4 32.3•215 6.54.0.0 98.14. 19.5 • 50.54. 3-2 P. divisum + + + + 212-3 4.25.7 x 35"74.4"1 36.04.3.9x 6.54.0-0 118-74. 13-7 • 44.34- 8.4 P. squammulatum + 176"84- 25"0 x 44-24- 2"7 58-9• 8-24.1-6 101-94. 15.1 • 49-54.9.5 Ab, abaxial; Ad, adaxial; +, present; -, absr 116 M Suryanarayana Raju, V Seshavatharam and S Appa Rao Table 2. Stomatal characters of the genus Pennisetum. Stomatal frequency Stomatal index Name of the speeies Stomatal size (q Abaxial Adaxial Abaxial Adaxial P. polystachyon 67"2+1-4• 78.94-12.3 17.74- 2'3 17"54- 0-0 5.0+1.4 P. americanum 66"84-1.5x30.44-I.0 72"04-22.2 46"74-14-3 14"24- 3"2 11-54-4"2 P. clandestinum 70"54-1"4x45"0+3.3 102"44-13.2 26"34-10"1 21"44- 2"7 7"24-2"4 P. pedicellatum 86"84-2.3x44-94-4.1 62"64-17-1 26"94-11-8 14"94- 2"4 8"34-2"7 P. orientale 61"24-3"6x31.8+2.9 202"54-22"3 57"44-19"5 15-04-10'3 5"54-1'5 P. villosum 65"44-1"4x43.5+1.4 96"54-16"2 45'34-19"8 18"54- 2"7 9"74-4"4 P. cenchroides 51"84-1"4x33-4+0.7 149"24-12-4 91"24-19"2 21-54- 1"7 10"94-2'3 P. purpureum x 59-54-1.7x35.94-1.6 144"04-14.6 87-84-22-2 16-54- 1-6 13"04-2"9 typhoides 0aybrid) P.