Proc. Indiaa Aear Sed. (Plartt Sed.), Vol. 91, Number 6, December 1982, pp. 473-478. I~) Printed in India. The floral anatomy of Puya spathacea Mez. (Bromeliaceae) with special reference to nectaries R A KULKARNI and R M PA[ Plant Morphol6gy Laboratory, Department of Botany, Marathwada University, Autrsngabad 431 004, India MS reeeived 25 May 1981 Abstraet. The floral anatomy of Puya spathacea /V[ez. is dr in detail. The outer floral whorls ate united, to develop a sltort hypanthium whieh is actnate to the baso of the ovary. The sopals aro five-traced, anct the petals, three-traeed. The placentation is axile. The oecurrenee of numerous avules in more than two rows as well as the extension of the earpellary ventrals into the style ate less advanced features. The avarian neetary is extensively developed and shows a transition between typic,3l septal and epigynous neetaries of aertain monoeoty- ledonous taxa. Keywords. Puya spathacea ; floral anatomy ; nectaries. 1. Introduction The Bromeliaoeae ate a fairly largo family with abaut sixty g~aera and about 2000 speeies. Hutchinson (1959) eonsiders the family to be a homogeneous taxon reprosenting the ' clŸ of a lino of deseent wherein the oalyx and oorolla have remained distinet of fairly distinct from eaoh other '. He treats ir as related to, but more advanr than the Commelinales. Smith's extensive studies (1934) point out that the family has strongest affinities with the Rapateaeeae and that both families probably arose from a eommon ancestral stoek. Within the family, Puya is treated as probably the souroe of ancestral types from whioh the other sub-famŸ developed. Aeoording to Pittendrigh (1948), Puya is the most primitive of living bromeliad genera. The genus Puya is a native of the Ar.des with unique habit and habitat. Some species of the genus ate considered to be the largest and most interesting of the bromdiads, e.g., Puya raimondii Harms, a rare monument of the Peruvian Andes threatened with extinotion. Plants of this speoies att~tin a height of 9"5 m and bear thousands of flowers with sugar-poor honey and p.~[liaated by birds. The tiny, winged seeds may number .ev~rt a biltion pzr pinar. The plants are mono- 473 P. (B)--I 474 R A Kulkarni and R M Pai 6arpi• and hapaxanthic (blooming once in their life and dying out thereaftet., and propagated exclusively by seed). Puya spathacea Mez. is a much smaller plant attairting a height of 1 m. Studies in the floral anatomy and morphology of this interesting group of plants aro moagre. An extensivo investigation on the vascular anatomy of the flower of the group is, therefore, undertaken in this laboratory, and the results on che of the most uniquo genera aro presented in this paper. Amongst the noteworthy earlier contributions on the family is a paper by Budnowski (1922) who is of the opinion that probably no Bromeliaeeao lack septal glancts. Some work on the group is in progress at Professor Rauh's laboratory in West Germany. 2. Mate¡ and methods The fixed flowering material was received from Prof. H Merxmuller, West Germany, oolleoted from bis University Botanic Gardens. The usual paratfin method has been followed. Serial transections (10-12/~ in thickness) and longi- seotions were stained with crystal violet using erythrosin as a counter stain. 3. Observations The pedicd contains a ring of six to eight prominent bundles surrounded by many discreto smaller strands (figure 1). AII these bundl•s divido and form nume- rous stran• which resolve into a largo number of centrally placed placental bundles and six outer groups of stra¡ from which the principal bundles of the flora/whorls emerge out (figure 2). From each of the posterior and antero-lateral groups of strands three ES st-rands aro derive& While the latemls amongst the three branch and extend into the sepals on either sido, the median che bifur- cates and branohes into the margins of both the sepals (figure 3). The remainder of these groups resolve into an inner IS bundle and an oute~ strand whioh splits into ah ~ bundlo and two LP strands (figure 4). The three groups in the postero- lateral and anterior positions resolv• into the MS, OS and D stmnds (figure 4) The nectary is developed from the very base of the ovary beneath the level of the loculi (figure 4). It is extensively developed with many canal- like passage ways and surrounded by the repeatedly dividing placental bundles (figures 3, 5). This giros the appearance of 'processes' of axile tissue of the ovary lined by glandular ceUs. Upwards, the neotary is • in the centre to result in three glandular clefts and some of the 'processes' persist in the forro of lobos of oarpeUary tissue enclosed in septal oavities of eanals. These open to the outside towards the middle of the length of the ovary (figure 6). The ovary is trilooular with the plaoentation axil• (figuro 6). Upwards, the margins of the carpels meet only in the centre to continuo syncarpy (figures 6, 7). Some of the placental bundles arrange themselves opposite to the loeuli and these bear traces into the placentae and the ovules (figures 6, 7). The ovules ate numerous and borne in many rows on each placenta. Most of the placental bundles emd in bearing traces to the ovules and towards the nectary. Six plaeental Floral anatomy of Puya spathacea Mez. ,475 t p-o<.'7 ~~91 5PAiP,~.EA~[~ Figures 1-5. Puya spathacea, serial transeetions of the flower from the base upwards ; D, carpellaxy dorsal ; ts, inner staminal strand ; LP, lateral bundle of l~etal ; LS, lateral bundle of sepal ; Me, median bundle of petal ; MS, median bundle of sepal ; N, nectary ; P, petal ; PL, placental bundles ; os, outer staminal strand ; s, sepal. 9~~~-3"'--~ ~~:- . >'M~~.-g.~" < Z~ :~--~~!" :-:~~~~ 9, .~~ f.~ ~-/ /~~ .~~./ ,~.~~_~ ,c_ Figures 6-11o Puya spathacea, serial transections of the uppr paxt of the flower ; qL, gland ; PL, placental bundles ; se, stylar canal ; st, stamcn ; s~z, style, 476 R A Kulkarni and R M Pai bundles (cmpeUary ventrals) continuo upwards into the base of the style (figure 8). The ovarian loculi continuo in the forro of three canals which merge into a triradiate canal in the style (figure 9). The earpellary dorsals continuo up to the tip of the style and into the three shallow stigmatie lobos. The outer floral whorls forro a short hypanthium which is adnate to the base of the ovary. The sepals, petals and stamens separate out simultaneously (figure 6). The sepals are twisted to the left and the petals to the right (figure 7). At the lovel of insertion, the sepals and the petals receive 8 of 9 traces (figure 5). The median bundles of the sepals and the petals bear lateral branches, somo of which may divide further. The six stamens aro one-traced. The staminal bundle extends upwards into the connective and ends at the base of the sho~t crest of the anther (figure 10). It bears a lateral branch towards either anther letra (figure 9). The anther is two-ceUed. The outer stamens are longer (figure 10). 4. Discussion The vascular anatomy of the flower of Puya presents several features of interest and importante. The outer floral whorls ate united into a short hypanthium which is adnato to the ovary for some length. This is a trend in the dovelopment of an inferior ovary whieh is characteristic of the allegedly advanced bromeliads, e.g., Aechmea, Billbergia, Cryptanthus, Neoregelia. The adnation is, however, not of a marked degree which is also roflected by the absence of fusion of the principal strands of the floral whorls. The placentation is axile. The ocourrence of numerous ovules borne in many rows is a primitive feature. The extension of the oarpellary ventrals into the style is a[so a less specialised condition. The dovelopment and the structural details of the neotary aro very sigrtificant. InitiaUy, the neotary is in the form of a central erater with oanal-like passageways which proliferate profusely. The plaoental bundles repeatedly divido and aro lodged in what appoar as 'proeesses' of carpeUary tissue lined by glandular ceUs. The plaeental bundks have to be associated with the neetary in its function (Agthe 1951 ; Budnowski 1922 ; Frei 1955 ; Pai and Tilak 1965 ; Tilak and Pai 1974). Upwards, the nectary is elosed in the oontre and the 'processes' of earpellary tis~ue appoar in the forro of distinct glandular outgrowths lodged in septal eavi- ties. These aro vaseula¡ by the plaeental bundles. The glandular lobos open to the outside. In Costus and Tapeinoehilus of the Costaceae a moro or less similar initial condition is observed which probably prompted Brown (1938) to describe the ne~aries in Costus as soptal. Rao et al (1954) describe them as not septal nectaries but as vaseularised outgrowths of carpoUary tissue which extend upwards in ovarian eanals along the septal radii and open at the top of the ovary. In Kaempferia rosca (Pai 1966) these glandular lobos appear on the septal rad¡ in similar but •piovarian canals at about the lovel where those in Costus ond, and r above the ovary. In the majority of zingibers, the n aro opigynous. It may be noted that in monocotyledonous taxa with extensively developed septal neotaries with oanal-like passageways, vaseularised ' prooesses' of earpellary tissue do oocur, e.g., Musa and Ensete (Tilak and Pai 1974). However, these Floral anatomy of Puya spathacea Mez. 477 do not develop into glandular outgrowths. This would seem to indicate that these ' processes' may persist and extend upwards as glandular lobes or outgrowths in some taxa as in Puya, Costus and Tapeinochilus.