Proc. Indian Acad. Sci. (Plant Sci.), Vol. 99, No. 2, April 1989, pp. 91-95. Printed in India.

Floral anatomy of the Liliaceae: Tribe Convailarieae

N P VAIKOS, S K MARKANDEYA and R M PAI Plant Morphology Laboratory, Department of Botany, Marathwada University, Aurangabad 431 004, India MS received 24 September 1987 Abstract. In both Convallaria and Theropogon, the tepals and stamens are one-traced. The placentation is morphologically and anatomically parietal. Convallaria has no floral nectary. Theropogon has it ovafian. Affinities of the tribe with the Polygonateae are indicated. Cronquist's assor of the seggregate families of the lilies under a larger alliance is thought to be more plausible. Keywords. Convallaria; Theropogon; floral anatomy.

1. lntroduction

In earlier contributions, the floral anatomy of some liliaceous tribes was presented (Vaikos and Pai 1982, 1986; Vaikos et al 1978, 1981, 1985). The present paper deals with the vascular anatomy of the flower of two monotypic genera of the tribe Convallarieae as circumscribed by Hutchinson (1973). The tribe Convallarieae comprises of 4 genera, e.g, Convallaria, Theropooon , Speirantha and Reineckea (Hutchinson 1973). Of these, Theropo9on occurs in Himalaya (Hooker 1894); Convatlaria is dist¡ in Europe and northern Asia and in the Alleghany mountains (Rendle 1930). The two genera are earlier examined embryologically (Stenar 1941, 1953; Bjornstad 1970) and palynologically (Erdtman 1952; Nair and Sharma 1965). Cheadle and Kosakai (1971) have described the vessels in Convallaria. Floral vasculature of Theropogon is descfibed by Utech (1979).

2. Materials and methods

The flowering material of Theropogon pallidus Maxim was collected from Khasi and Jaintia hills, Meghalaya, while that of Convallaria majalis L. was obtained from Suomi Finland. The plant material was fixed in FAA. The usual paraffin embedding method was followed. Se¡ transections (8-12/~m) were stained in crystal violet using erythrosin asa counterstain.

3. Results

The vascular bundles arranged in a ring in the pedicel become laterally interconnected upwards and bear the traces to the tepals and stamens in quick succession (figures 1-3, I1, 12). The remaining axial vascular tissue resolves into 3 carpellary dorsals and the carpellary ventrals. The latter are 6 in Convallaria and 3 in Theropo9on (figures 3, 13). The tepals are free in Theropogon (figures 13-17) and united into a prominent tube in Convallaria (figures 3-7). They are in two whorls. Each of them is one-traced (figures 3-9, 13-17). 91 92 N P Vaikos, S K Markandeya and R M Pai

Figures 1-10. Con•aUaria majalis. 1-9. Transections of the flower from the base upwards. 10. Transection of the abnormal flower.

The stamens are free in Theropogon (figure 13) and adnate to the tepals in Convallaria (figures 3-6). The stamens ate one-traced (figures 3-7, 13-18). The anther is two-celled, introrse and basi-fixed. There is a short crest for the anther in Theropo#on (figure 20). The gynoecium is shortly stipitate (figures 3, 13). The ovary is trilocular at the base and unilocular in the uppr part (figures 4-6, 10). In Theropogon, it becomes Floral anatomy of the Liliaceae: Tribe Convallarieae 93

Q

1mm (D 20

Figures I1-20. Theropogonpallidus. Transections of the flower from the base upwards. (CV, Carpellary ventral; D, carpellary dorsal; IS, innr staminal strand; MIT, median bundle of an inner tepal; MOT, median bundle of ah outer tepal; N, nectary; OS, outer staminal strand; STY, style). 94 N P Vaikos, S K Markandeya and R M Pai trilocular again at the top (figures 14--17). The ovules ate many and are arranged in two rows (figures 4, 5, 15, 16). The 6 carpellary ventrals merge into 3 strands in Convallaria (figure 4). Theropogon has only 3 bundles. These 3 bundles are lodged on the septal radii and bear traces to the ovules of adjacent carpels (figures 4, 5, 14-16). The carpeUary ventrals end in bearing traces to the ovules. The ovarian loculus/loculi continue into the style as an initial Y-shaped structure lined with transmitting tissue; this becomes circular in outline upwards (figures 7-9, 18). The style receives only the 3 carpellary dorsals. The style is shorter in Theropogon (figures 18, 19). Convallaria has no ovarian nectaries. Rather it appears to lack floral nectaries. In Theropogon, nectaries are develolaed atop the ovary as narrow grooves in the ovary wall on the septal radii (figure 17). The abnormal flower of Convallaria shows the occurrence of 5 tepals, 5 stamens and two antero-posterior carpels. The ovary is unilocular with the ovules on two parietal placentae (figure 10). The anatomy of the flower conforms with the anomalies noted.

4. Discussion

Vascular anatomy of the flower reveals some interesting features. The tepals in both the plants ate one-traced, and are anatomically similar. The stamens are also one- traced organs. The presence of a short crest for the anther noted in Theropogon appears to be of little phylogenetic significance (Vaikos 1984; Vaikos et al 1985). In Theropogon the ovary is trilocular at the base and the top and unilocular in the middle. This may be considered in terms of a 'spatial problem' (cf. Puri 1952). In Convallaria, the ovary is trilocular at the base and unilocular upwards. The location and behaviour of the carpellary ventrals is indicative of the type of placentation. The latter, on both morphological and anatomical grounds, is best considered as parietal. The development of the nectary, in Theropogon, asa short narrow groove in the ovary wall along the septal radius is interesting. Such a development is rather uncommon amongst the lilies. Occasionally, the liliaceous flower develops no floral nectary and the insect visitor is merely a pollen-forager (Chlorophytum tuberosum, Vaikos and Pai 1981). Convallaria has no floral nectary and the visiting bee performs a similar function (Rendle 1930). Affinities between the Convallarieae and Polygonateae have been suggested by Sen (1975) on the basis of similafities of chromosomes in Convallaria and Smilacina. The embryological studies of Bjornstad (1970) reveal that these two tribes are closely aligned. Therman (1956) does testify to the close relationship between these two tribes. One-traced tepals, parietal placentation, similar nectary development in Theropogon and Smilacina (N P Vaikos and R M Pai, unpublished results) are features that Convallarieae share with Polygonateae. It may, however, be noted that certain genera of Polygonateae, e.g. Disporum stand out distinct in this regard (N P Vaikos and R M Pai, unpublished results). Hutchinson (1973) considers the Convallarieae asa climax group. Recent taxonomic endeavours sharply circumscribe the traditional lilies into smaller apparently homogeneous entities and resort to varied taxonomic treatments of the Hutchinsonian tribes. While Dahlgren et al (1985) have the Convallarieae, Floral anatomy of the Liliaceae: Tribe Convallarieae 95

Polygonateae, Ophiopogoneae and Aspidistreae in their family Convallariaceae, Takhtajan (1980) adds Streptopodeae and Peliosantheae to the above 4 and includes all of them under the subfamily Convallarioideae of family Asparagaceae. The present authors, in the light of their personal observations on some liliaceous tribes are, at the moment, more at home with the lumper approach of Cronquist (1981) submerging most of the seggregate families within the Liliaceae, pending a further study on some tribes and publ/cation of results on some others.

Aeknowledgement

The authors are grateful to Dr I Kukkonen, Suomi, Finland, for the supply of the flowering material of Convallaria.

References

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