Proc. Indian Acad. Se]. (Plant Sei.), Vol. 96, No. 3, August 1986, pp. 233-239. Printed in India.

The floral anatomy of Gloriosa superba L. and Tricyrtis pilosa Wall. (Liliaceae)

N P VAIKOS and R M PAI Plant Morphology Laboratory, Department of Botany, Marathwada University, Aurangabad 431 004, India MS received 24 January 1986; revised 13 June 1986 Abstraer. In both the taxa, the tepals are 3-traced and the extrorse stamens ate one-traced. The placentation is parietal. The bases of the 6 tepals (Gloriosa) or the outer tepals (Tricyrtis) ate nectariferous. These appear like 'pouches"or 'sacs'. The increased branching of the traces at the base of the outer tepals in Tricyrtis and of both the whorls in Gloriosa is related with the development of the nectaries. The study reveals that both genera ate rather elose and a.re more at home together in a taxonomie erttity. Keywords. Gloriosw,,Tricyrtis; floral anatomy; tepaline nectaries.

1. Introduetion

The genera Gloriosa and Tricyrtis belong to the Uvula¡ and Tricyrtideae, the two nearby tribes of Hutchinson's (1973) Liliaceae. In India, both the taxa are represented by a single species each (Hooker 1894). Earlier publications on Gloriosa and Tricyrtis mainly concern the stamens and carpels (Troll 1931; Buxbaum 1937, 1960; Baum 1949; Joshi 1939; E1-Hamidi 1952; Sterling 1975, 1978; Rangarajan and Swamy 1980). The present account deals with the detailed vascular anatomy of the flower of Gloriosa superba L and Tricyrtis pilosa WaU. with an emphasis on the floral nectaries.

2. MaterŸ and methods

The flowers of G. superba were collected from plants cultivated in the Botanical Garden of Marathwada University, whereas those of T. pilosa were obtained from Khasi and Jaintia Hills, Meghalaya. These were fixed in FAA. The usual paraffin embedding method was followed. Serial transections cut at 8-14 #m thickness were stained in crystal violet using erythrosin asa counterstain.

3. Observations

3.1 Gloriosa

The pedicel in G. superba contains two rings of vascular bundles, each with 6 strands along with a few tiny bundles (figure 1). Each of the bundles of the outer ¡ divides into three strands of which the middle one extends as the median bundle of the tepals (figure 2), whereas the laterals traverse into the margins of the same tepal. Further up, the btmdles of the inner ring divide once or twice and bear six traces which bifureate

233 2.,4 N P Vaikos and R M Pai and extend into the margins of adjacent tepals (figure 3). The 6 staminal strands are next derived (figure 4). The remaining vascular tissue resolves into the 3 carpellary dorsals and 6 carpeUary ventrals (figure 4). The outer tepals separate first (figure 5) followed by the inner tepals and the stamens. The tepal strands continue to ramify in their upward course so that each tepal contains 12-15 bundles. The tepals are medianly ridged on their back (figures 5-8). The nectaries are tepaline and are developed from their base, p¡ to their separation, so that transections show a ¡ of 6 cavities (figure 4). The separation of

lmm

Figures l-& Gloriosasuperba. Transectionsof the flowerfrom the base upwards. Floral anatomy of Gloriosa and Tricyrtis 235 the tepals leaves a characteristic median "pouch' lined by nectariferous tissue (figures 5, 6). The stamens are simultaneously antheriferous and are neafly of the same length. The anthers are extrorse and two-celled. The stamens are one-traced (figures 6-11). Within the ¡ the staminal strands bear two temporary lateral branches (figure 8). The staminal strands end beneath the tip of the anther (figure 11). The non- vascular connective ends along with the anther lobes (figure 11). The ovary is trilocular (figures 6, 7) fora short length at the base. The ovules are

ii ii ~ll i ,so",; % -'.~Lr/

'~

18

Figttres 9-24. 9-12. Gloriosa superba. 13-24. Tricyrtis pilosa. Transections of the flower Ÿ the base upwards. Abbreviations used infieures: CV, carpellary ventral; D, carpellary dorsal; IS, inner staminal strand; LIT, lateral bundle of ah inner tepal; LOT, lateral bundle of ma outer tepal; MIT, median bundle of ah inner tepal; MOT, median bundle of aa outer tepal; N, nectary; OS, outer staminal strand; PL, placenta] bundle; SC, stylar canal; STG, stigma; STY, style. 236 N P Vaikos and R M Pai borne in two rows in each loculus. The 3 placental bundles, a product of fusion of ventrals of adjacent carpels, lie on the alternate septal radii (figure 6). These split and bear traces to the ovules of adjacent carpels (figures 7, 8). The placentae separate a little above the base of the ovary to render it unilocular (figure 8) for the rest of its length. The placental bundles continue to bear traces to the ovules. They extend into the base of the style (figure 10). The carpeUary dorsals may bear sporadically a few lateral and the placental bundles a few outer branches in their upward course (figures 7-9). These end at the top of the ovary of at the base of the style (figure 10). The carpellary dorsals alone extend into the style. The ovary becomes t¡ at its tip once again (figure 10). The ovarian loculi are continued in the form of 3 cavities which merge in the basal part of the style to forma triradiate canal (figure 11). It is lined with transmitting tissue. The placental bundles end in the basat part of the style. The ovary is deeply 3-grooved and this condition is maintained within the style. The style splits into 3 stigmatic segments along these grooves (figure 12). Each of them receives a carpellary dorsal.

3.2 Tricyrtis

The floral axis in T. pilosa contains a ring of 3 large and 3 small bundles alternating with each other. In addition, 6 smaller bundles ptaced slightly to their outside alternate with them (figure 13). The latter and the 3 large bundles divide a few times and forro 3 groups of 8-10 strands (figure 14) from which the 6 bifurcating lateral traces to outer tepals, the 3 medians and the 6 lateral bundles to inner tepals and the 6 staminal strands emerge in quick succession (figures 15-17). The 3 smaller bundles of the ring in the pedicel extend as the median bundles of outer tepals (figure 14). The remaining vascular tissue resolves into 3 carpellary dorsals and 6 carpellary ventrals (figure 17). The outer tepals separate first (figure 17) followecl quickty by the inner tepals and the stamens (figure 18). The tepal strands show high ramification at the base of the outer 3 tepals as compared to the inner tepals (figures 16, 17). Each outer tepal thus contains 12-15 bundles whereas each inner tepal receives about nine strands (figures 17-20). The outer tepals are larger than the inner. The bases of the outer tepals ate sac-like and are nectariferous (figure 17). The inner tepals have an outer median ¡ (figures 18-20). Each of the stamens receives a single bundle (figure 18). The filaments of the inner stamens are comparatively narrow. The stamens are antheriferous almost simultaneously; the 3 outer stamens are slightly shorter (figure 23). The vascular bundle within the filament continues upwards into the connective without a division (figures 18-23) and ends beneath the tip of the anther (figures 22, 23). The non- vascular connective splits into two and ends along with the two anther lobes (figures 23, 24). The anthers are extrorse and two-celled. The ovary is shortty stipitate (figure t8). It is unilocular from the base (figures 19, 20). In some flowers examined, the ovary is trilocular for ala extremely short length at the base. The two carpellary ventrals of adjacent carpels are lodged on the alternate septal radii and these fuse to form the composite placentat bundles (figure 20). They bear traces to the ovules (figure 20). Floral anatomy of Gloriosa and Tricyrtis 237

The 3 placental bundles are not exhausted in bearing traces to the ovules. These 6 bundles extend into the style (figure 21). The ovarian Ioculus is continued into the style as the stylar canal (figure 21). It is lined with transmitting tissue. Within the style, the 3 placental bundles end first (figure 22). The 3 carpellary dorsals extend upwards up to its tip (figures 23, 24). The triangular style develops 3 prominent elongate lobed 'arms' (figure 24). The carpellary dorsals bifurcate and extend into the 'amas' and end (figure 24).

4. Discussion

The 6 free perianth segments are arranged in two whorls. In Gloriosa, these tepals are more or less of the same size and all have a median ridge on their back. In Tricyrtis only the tepals of the inner whorl are with a median ridge on their outer side and these ate also comparatively narrow. The tepals are 3-traced. This is thought to be a derived condition from a one-traced type (Vaikos et al 1985). Seeretion of nectar is ah adaptation to pollination. In both the plants, the tepals bear the nectaries. Ir all the 6 tepals have nectaries at their base in Gloriosa, the bases of the outer tepals alone have them in Tricyrtis, The outer tepal strands ramify profusely and bear a few branches into the nectariferous sacs as well. The inner tepal strands do not show such high ramification. In Gloriosa the tepal strands of both whorls ramify, although not to the same extent as in Tricyrtis. The branching of the tepal traces is related to the bearing of necta¡ Furthermore, the phloem in these bundles is a more prominent strand. Agthe (1951) draws attention to the association of vascular tissue with the nectary in Fritillarut. In this genus also the nectaries are tepaline. During her survey of analysis of nectar types, Percival (1961) has reeorded sucrose as dominant in the nectar of Gloriosa ftower. It may be noted that there do exist many instances in the lilies, where ordy a s~ngle tepal whorl is nectafiferous. It may be the outer whorl as in Tricyrtis of the inner as in Calochortus. This is, of late, been found to be an important taxonomic parameter for delineating Calochortaceae (Dahlgren et al 1985). The development of tepaline nectaries is a less specialised character (Fahn 1953). However, Dahlgren and Rasmussen (1983) and Dahlgren et al (1985) ate of the opinion that these nectaries represent a derived condition. The present authors would offer their comments in this regard in a subsequent communication. Suffice it is just to mention that they are more in accord with Fahn (t953). The stamens are free in both the ptants. However, Hooker (1894) and Hutchinson (1973) describe them as connivent in Tricyrtis. The stamens are one-traced. In Tricyrtis latifolia the staminal strand bifurcates (Sterling 1978). This is taken by Sterling to indicate the stamen asa fusion product of two microsporophylls. There is no division of the staminal strand in the species of the genus presently studied. In Gloriosa, the staminal strands in the filaments show a division into 2-3 bundles. They fuse to forro a single bundle within the connective. Joshi (1939) reports the occurrence of intrafaseicular cambium activity of the staminal strands in Gloriosa, which he takes as a vestigeal character. He is of the opinion that the repeated bifurcation of the staminat bundle is indicative of the fact that the stamen is derived from a dichotomously dividing branch system with terminal sporangia. 238 N P Vaikos and R M Pai

In numerous petaloid monocotyledonus taxa, a temporary division of the staminal strand as above is observed (Kulkarni 1973; Markandeya 1978; Patil 1983; Tukshetty 1969; Vaikos 1974). In scitaminean taxa, the staminal strand divides a few times, so that the filament has 5-8 large bundles (Tilak 1967; Tilak and Pai 1974). One should not read too much in this division of the staminal strands to arrive at adventurous, far-fetched deductions. The stamens are more of less of the same length in Gloriosa. In Tricyrtis the outer whorl of stamens is slightly shorter. A further differentiation of the two whorls hato members of two distinct sizes is characteristic of many liliaceous genera, e.g., Scilla, Hemerocallis, Kniphofia and the Aloineae, Allieae etc. (Markandeya 1978; Vaikos t974; Vaikos and Pai 1982; Vaikos et al 1978, 1981, 1985). This represents a trend towards differentiation of the two whorls, which is expressed in various degrees among the liliaceous t¡ resulting ultimately in the reduction of either whorl of stamens both amongst the lilies and the more specialized taxa of the petaloid monocotyledons (Markandeya 1978; Pai 1966; Pande and Singh 1979; Rao 1969, 1974; Tukshetty 1969). The extrorse anthers are characteristic of both these plants. This is rather a less common feature amongst the lilies. The ovary is superior. It is shortly trilocular at the base and unilocular upwards in Gloriosa. In Tricyrtis it is generally unilocular throughout; sometimes it is trilocular at the base (Hutchinson 1973). In unilocular gynoecia the ovary does show loculation at the base (Puri 1952). In Gloriosa, the ovary becomes t¡ again at the very top of the ovary. This is a case of 'spatial problem' (Puri 1952). Each carpel receives a 3-traced supply. Three pairs of carpellary ventrals are on the altemate septa~l .-adii. The members of each pair usually unite to forro 3 composite bundles, which supply to the ovules of adjacent carpels. The placentation is parietal on morphological and anatomical grounds. The style receives the carpeUary dorsals and the carpellary ventrals, although the latter end early. The extension of the ventrals into the style is a less advanced feature. The style is split into 3 segments in both the plants. In Tricyrtis, eaeh elongate segment is bilobed and each lobe receives a branch from the carpetlary dorsal. A close perusal of the floral morphological features would reveal that both the genera stand rather closely aligned and should be more at home together. Hutchinson (1973) treats the Uvularieae (Gloriosa) and the T¡ (Tricyrtis) in close sucr Recent treatments (Takhtajan 1980; Dahlgren et al 1985) variously treat these genera. There seems to be more in common between the two than meets the eye to put the two genera under one roof. Contemporary taxonomists may find the data worthy of note in further formulating their oft-revised taxonomic treatments of tiliaceous genera.

References

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