Cytologia 39: 419-427, 1974 Cytological Studies in Ottelia alismoides Pers.1 M. P. Misra Post-Graduate Department of Botany, Magadh University, Bodh Gaya, Bihar, India Received November 20, 1972 The systematic status of Helobiae of Engler and Prantl (1936) to which Ottelia alismoidesPers. belongs has been subjected to considerable debate by taxonomists. In the two phylogenetic systems of classification, namely that of Engler and Prantl and that of Hutchinson, the position of this order varies significantly. Engler and Prantl considers Pandanales to represent the starting point of monocotyledons, me mbers of the order Helobiae being considered as advanced genera. On the other hand, Hutchinson, a champion of the reduction theory con siders the apparent simplicity in the floral structures of Pandanales of monocoty ledons is not due to primitiveness but due to extreme specialization and reduc tion. According to him, the two principal orders of Helobiales namely Alismatales and Butomales have been regarded as the two starting points of monocotyledons from which other orders of monocotyledons have been derived. He further stressed the origin of these two orders from Ranales of dicotyledon. In such case of taxonomic disputes, cytological evidences often provide with a good indication of phylogenetic relationship. Several workers have no doubt tried to deal with the cytology of the different members of Helobiae, Harada (1956), Sharmaand Bhattacharya (1956),Pogan (1961, 1962), Larsen (1963), Gadella and Kliphius (1963) practically no work has been done to study the karyotypes of Otteliaalismoides in relation to its different habitate. In this case high incidence of different degree of polyploidy have been obtained. No attempt has either been made to correlate such polyploidy with their ecological conditions or to find out the extent to which structural alterations too are associated with this polyploidy. In view of the possibilities mentioned above the present investigation was taken up. In the present scheme of work not only a detailed karyotype study has been made but on th basis of present and previous records, an attempt has been made to present a cyto-taxonomical picture of this group with special emphasis on the lines of evolution. Materials and methods Plant materials were collected from two different localities of Bihar and eight different localities of Bengal as detailed below: I. Plants collectedfrom Bihar 1 This work was undertaken for the Ph . D. thesis. Part of the work was carried on in the Cytogenetics Laboratory of Calcutta University, Calcutta, India. 420 M. P. Misra Cytologia 39 1. Plant type A collected from Sahjangi Pond at Bhagalpur Plants with elliptica leaves without spines on the margin of the petioles. 2. Plant type B collected from a Pond at Patna Plants with cordate leaves with spines on the margin of petioles. II. Plants collected from Bengal 1. Kalyani lakes near Calcutta type Kl Plants with more or less lanceolate type of leaves, wavy in outline. 2. Kalyani lakes near Calcutta type K2 Normal type with cordate leaves, spines on the margin of petioles. 3. Kalyani lakes near Calcutta type K3 Plants with Vallisneria like leaves without spines, showing meiotic irregularities 4. Kalyani lakes near Calcutta type K4 Plants with screwpine like leaves. 5. Kalyani lakes near Calcutta type K5 Plants with more or less reniform leaves at the top and lanceolate leaves below, with spines on the margin of petioles. 6. Indian Botanical Gardens at Shibpur type G1 Plants with linear leaves with spines on the margin of petioles. 7. Indian Botanical Gardens at Shibpur type G2 Plants with large more or less reniform leaves with spines on the margin of petioles. 8. Indian Botanical Gardens at Shibpur type G3 Plants with elliptical leaves without spines on the margin of petioles. Somatic preparations were made of healthy roots. They were first pretreated in different pretreatment chemicals such as 0.5% colchicine solution, 0.002M oxyquinoline solution, saturated para-dichlorobenzene and aosculine solution and various combination of above chemicals. It was however found that 0.002M oxyquinoline saturated with aesculine was found to be most suitable pretreatment chemical in this case. Healthy root tips were cut and pretreated with a mixture of 0.002M oxyquinoline saturated with aesculine at 0•K-5•Ž for 3-5 minutes and then transferred to and kept in cold (10•K-12•Ž) up to 3 hours. They were fixed in acetic alcohol (1:3) mixture for one hour and then kept in 45% acetic acid solution for 10 minutes followed by staining and squashing as usual. The magnification of the figure drawn was•~2100. The chromosome with secondary constrictions were drawn in out-lines. Photographs were taken from temporary preparation and were suitably enlarged. Observations The somatic chromosome numbers of the different plant types so far investi gated have been found to be 2n=44, 2n=66 and 2n=Ca 132. A detailed karyo type analysis of different plant types reveals a difference in the position of the secondary constriction. Though the chromosomes are of well graded series, yet the size difference is well marked, ranging from 12 .5ƒÊ to 2.75ƒÊ. On the basis of 1974 Cytological Studies in Ottelia alismoides Pers. 421 Figs. 1-6. la, Ottelia alismoides (type A) . Somatic metaphase plate showing 2n=66 chromosomes (•~2100) and its idiogram respectively . 2, O. alismoides (type B). Showing 33 bivalents in the metaphase 1. •~2100 . 3, O. alismoides (type CK1). Showing 22 bivalents at meiotic met aphase 1. •~2100 . 4, O. alismoides (type KC2). Somatic metaphase plate showing 2n=66 chromosomes . •~2100. 5, O. alismoides (CK2). Showing 33 bivalents in meiotic metaphase 1. •~2100 . 6, O. alismoides (type CK4) showing 32 bivalents and two univalents at meiotic meta phase 1. •~2100. 422 M. P. Misra Cytologia 39 relative length of the chromosomes, they can be divided into five different groups viz. very long, long, medium, short and very short types. The main chromosome types which have been observed here are as follows: Type A: Very long to long chromosomes with median to nearly median primary constrictions. Figs. 7-9. 7, O. alismoides (type CK5). Somatic metaphase plate showing 2n=Ca 132 chromo somes. •~2100. 8-8a, O. alismoides (type DG1). Somatic metaphase plate showing 2n=44 chro mosomes (•~2100) and its idiogram respectively. 9-9a , O. alismoides (tyoe DG2). Somatic meta phase plate showing 2n=66 chromosomes (•~2100) and its idiogram respectively. Type B: Long to medium chromosomes ranging from 9 .5ƒÊ to 3.0ƒÊ with subter minal primary constrictions. Type C: Long to medium chromosomes each two constrictions , primary and secondary, one located at submedian region , the other at subterminal 1974 Cytological Studies in Ottelia alismoides Pers. 423 at the distal end of the short arm. Type D: Medium sized chromosomes, ranging from 7.0ƒÊ to 2.5ƒÊ, with median primary constrictions. Type E: Comparatively long chromosomes each with a submedian primary constriction and a satellite at the distal end of one arm. Type F: Medium sized chromosomes, ranging from 6.25ƒÊ to 2.4ƒÊ with subtermin - al primary constrictions. Type G: Medium sized chromosomes, each with two constrictions, primary and secondary, one situated at the submedian region, the other at the subterminal position at the distal end of the short arm. Type H: Short to very short chromosomes ranging from 4.25ƒÊ to 2.25ƒÊ, with nearly median to subterminal primary constrictions. Type I: Very short chromosomes with subterminal primary constrictions. The different plant types differ in having different combinations of the above types. A detailed description of the somatic components of the different plant types studied here is given below: I. Plant type A collected from Bihar 2n=66 C8+D10+E4+F12+H24+I8 (Figs. 1 and la). 2. Pond at Patna Only meiotic preparation could be made. Meiotic metaphase I shows 33 bivalents with regular separation. The size of the PMC is 98.1ƒÊ in length and 63.7ƒÊ in breadth. Thus it is the largest PMC recorded here (Fig. 2). II. Plant types collcted from Bengal 1. Kalyani lakes (type K1) Only the meiotic preparation could be made, The PMC shows n=22 at metaphase I. The size of the PMC is 64.47ƒÊ in length and 32.3ƒÊ in breath (Fig. 3). 2. Kalyani lakes (type K2) 2n=66=A2+B2+C4+D8+F28+G2+H14+I8 (Fig. 4) The meiotic preparation shows a large PMC 63.75ƒÊ in length and 56.1ƒÊ in breadth, with a large prominent nucleous, slightly away from the centre, with n=33, one pair of bivalents are in contact with the nucleolus (Fig. 5). 3. Kalyani lakes (type K3) Only meiotic preparations could be made. Meiosis shows various irregu larities such as early separation and laggers of bivalents as well as univalents (Figs. 14, 15 and 16). 4. Kalyani lakes (type K4) Only meiotic preparation could be made . The PMC shows n=33, composed of 32 bivalents and two univalents . The size of the PMC is 71.06ƒÊ in length and 64.47ƒÊ in breadth (Fig . 6). 5. Kalyani lakes (type K5) 2n=Ca 132 (Fig. 7) Only the somatic number could be counted , which is 2n=Ca 132. The 424 M. P. Misra Cytologia 39 chromosomes are very small in comparison to other types. A variation number of 2n=66 has also been observed in this case. 6. Indian Botanical Garden, Shibpur (Bengal) (type G1) 2n=44=A10+B16+D6+F12 (Figs. 8 and 8a). 7. Indian Botanical Garden, Shibpur (type G2) 2n=66=A10+B4+C4+D10+F26+H6+I6 (Figs. 9 and 9a) The meiotic metaphase shows n=33 with regular separation. The size of the PMC is 70.125ƒÊ in length and 52.225ƒÊ in breadth (Fig.