ONTOGENY AND PHYLLOTAXIS OF THE TERMINAL VEGETATIVE SHOOTS OF MICHELIA FUSCATA

Tucker Shirley C. (Northwestern U., Evanston, Ill.) Ontogeny and phyllotaxis of the terminal vegetative shoots of Michelia fuscata. Amer. Jour. Bot. 49(7): 722–737. Illus. 1962.—Two patterns of symmetry occur in Michelia fuscata In the lead shoots, leaves arise in a 2/5 spiral arrangement which may be either clockwise or counterclockwise. Other shoots are dorsiventrally organized; these shoots produce leaves in a modified ½ phyllotaxis in which the angle between the 2 files of leaves lies between 100° and 150°, according to the particular branch. Both types of shoot have a zonate apical meristem with a biseriate tunica a central initial zone, and a peripheral zone. The apical configuration of cells does not change appreciably during the plastochron. The flat to low-convex outline of the shoot apex is maintained by initiation of the leaves close to the summit of the apex; the diameter of the meristem diminishes greatly after such an initiation. Leaf inception in the subsurface tunica layer is followed by precocious activity of the marginal meristems which extend the stipular flanges completely around the base of the apical meristem. The stipular margins then fuse laterally and form a hood over the apex. A subapical initial meanwhile is active in the leaf blade, where it persists up to the time the leaf is 2 mm high. The most recent primordium is 300 μ high before another leaf is initiated. The vascular system of the stem is a cylindrical network of leaf traces, with 6–12 traces per leaf. The procambium develops acropetally from preexisting vascular strands in the stem below. Elements of the diverse sclereid system differ in shape in different tissues, according to the availability of intercellular space. Goebel's term “Pendelsymmetrie” is discussed with reference to apical activity in Michelia.     

PHYLLOTAXIS AND VASCULAR ORGANIZATION OF THE CARPELS IN MICHELIA FUSCATA

Tucker , Shirley C. (U. Minnesota, Minneapolis.) Phyllotaxis and vascular organization of the carpels in Michelia fuscata. Amer. Jour. Bot. 48(1): 60–71. Illus. 1961.—Phyllotaxis pattern and vascular organization are closely related in the floral receptacle of Michelia fuscata (Magnoliaceae). The carpels arise in a spiral or helix. They are initiated alternately along each of 7, 8 or 10 helical parastichies according to a complex repetitive sequence. The pattern of the dorsal carpellary trace fusions is orderly for each of the 10 flowers investigated. The dorsal carpellary traces in each parastichy diverge from the same vascular sympodium. Among flowers one finds differing numbers of parastichies, differing angles of divergence, and varying sequences of parastichies which reflect the order of carpel initiation. The angle of divergence, although consistent for any 1 parastichy in a flower, can vary greatly between parastichies. The nature and importance of the organizers which determine appendage position at the apical meristem are considered. Changes in apical size, configuration, and activity are shown to be related to phyllotaxis.     

DEVELOPMENT AND PHYLLOTAXIS OF THE VEGETATIVE AXILLARY BUD OF MICHELIA FUSCATA

Tucker, Shirley C. (Northwestern U., Evanston, III.) Development and phyllotaxis of the vegetative axillary bud of Michelia fuscata . Amer. Jour. Bot. 50(7): 661–668. Illus. 1963.—The vegetative axillary buds of Michelia fuscala are dorsiventrally symmetrical with 2 ranks of alternately produced leaves. The direction of the ontogenetic spiral in each of these buds is related both to the symmetry of the supporting branch and to the position of the bud along the branch. On a radially symmetrical branch, all the axillary buds are alike—all clockwise, for example. But in a dorsiventrally organized branch the symmetry alternates from clockwise in 1 axillary bud to counterclockwise in the next bud along the axis. Leaf initiation and ontogeny of the axillary apical meristem conform with those of the terminal vegetative bud. The axillary bud arises as a shell zone in the second leaf axil from the terminal meristem. During this process the axillary apex develops a zonate appearance. The acropetally developing procambial supply of the axillary bud consists wholly of leaf traces. At the nodal level the bud traces diverge from the same gap as the median bundle trace of the subtending leaf. Only the basal 1–2 axillary buds which form immediately after the flowers elongate each year, while the majority remains dormant with 3 leaves or fewer.     

ORGANOGENESIS IN THE CARPELLATE FLOWER OF DRIMYS LANCEOLATA

This study of floral development in Drimys lanceolata in Section Tasmannia provides a basis for comparison with D. winteri, a member of the section Wintera, which has been described previously. The carpellate flowers of D. lanceolata have 2 sepals, 4–6 petals, and a solitary carpel, which form in acropetal succession. In symmetry the flower and its apical meristem are bilateral rather than radial, as in the flower of Drimys winteri. The floral apex of D. lanceolata is zonate while that of D. winteri is organized as a mantle and core. Preceding carpel initiation the floral apex of D. lanceolata is narrowly wedge-shaped, while that of D. winteri is low-convex. The entire apex is utilized in carpel initiation in D. lanceolata, involving many subsurface cell divisions over the entire summit. No apical residuum remains, and the carpel is terminal. In this feature the contrast with D. winteri is particularly marked, since in the latter, carpels are initiated laterally around the floral apex, which c an be recognized as an apical residuum after all appendages have formed.     

FLORAL DEVELOPMENT OF COCHLOSPERMUM TINCTORIUM AND BIXA ORELLANA WITH SPECIAL EMPHASIS ON THE ANDROECIUM

The initiation and development of the flower of Bixa orellana L. and Cochlospermum tinctorium A. Rich, were investigated using the scanning electron microscope to elucidate the nature of the androecial development and the relationships of both taxa. Initiation of floral buds starts with the inception of five sepals in a 2/5 sequence between two bracteoles. The petals are formed successively on the irregular pentagonal apex in a phyllotactic pattern different from that of the calyx. Stamen development proceeds centrifugally on a broad circular primordium or ringwall, which attains its final size at the time of initiation of individual stamens. Stamen primordia arise in successive whorls without connection to the perianth. The residue of the apex is differentiated into a gynoecial circular primordium. In Cochlospermum 3 to 4 carpels are initiated; in Bixa no individual carpels are visible. The origin of the androecial circular primordium is discussed in relation to other types of androecial development. A comparison is made with existing theories of the evolution of multistaminate androecia. Few differences were found in the floral development of Bixa and Cochlospermum, except in the gynoecium. It is proposed to retain them in a single family Bixaceae for a number of reasons. The floral development supports a thealean, dillenialean, or violalean affinity rather than a malvalean. The inception of a broad androecial circular primordium is highly different from the development in Malvales, where more space for stamens is provided by the continuous growth of a tube.     

Arabidopsis thaliana CENTRORADIALIS homologue (ATC) acts systemically to inhibit floral initiation in Arabidopsis

Floral initiation is orchestrated by systemic floral activators and inhibitors. This remote‐control system may integrate environmental cues to modulate floral initiation. Recently, FLOWERING LOCUS T (FT) was found to be a florigen. However, the identity of systemic floral inhibitor or anti‐florigen remains to be elucidated. Here we show that Arabidopsis thaliana CENTRORADIALIS homologue (ATC), an Arabidopsis FT homologue, may act in a non‐cell autonomous manner to inhibit floral initiation. Analysis of the ATC null mutant revealed that ATC is a short‐day‐induced floral inhibitor. Cell type‐specific expression showed that companion cells and apex that express ATC are sufficient to inhibit floral initiation. Histochemical analysis showed that the promoter activity of ATC was mainly found in vasculature but under the detection limit in apex, a finding that suggests that ATC may move from the vasculature to the apex to influence flowering. Consistent with this notion, Arabidopsis seedling grafting experiments demonstrated that ATC moved over a long distance and that floral inhibition by ATC is graft transmissible. ATC probably antagonizes FT activity, because both ATC and FT interact with FD and affect the same downstream meristem identity genes APETALA1, in an opposite manner. Thus, photoperiodic variations may trigger functionally opposite FT homologues to systemically influence floral initiation.     

DEVELOPMENT AND VASCULATURE OF THE FLOWERS OF LOPHOTOCARPUS CALYCINUS AND SAGITTARIA LATIFOLIA (ALISMACEAE)

The development of the bisexual flower of Lophotocarpus calycinus and of the unisexual flowers of Sagittaria latifolia has been observed. In all eases floral organs arise in acropetal succession. In L. calycinus, after initiation of the perianth, the first whorl of stamens to form consists of six stamens and is ordinarily followed by two alternating whorls of six stamens each. The very numerous carpels arc initiated spirally. In the male flower of S. latifolia the androecium develops in spiral order. A few rudimentary carpels appear near the floral apex after initiation of the stamens. There are no staminodia. The female flower has a similar developmental pattern to that of Lophotocarpus except that a prominent residual floral apex is left bare of carpels. The vascular system in all flowers is semiopen, with vascular bundles passing to the floral organs in a pattern unrelated to the relative positions of those organs. The androecia of these two taxa are similar to those of some Butomaceae and relationships based on ontogeny and morphology are suggested. The gynoecia are meristically less specialized but morphologically more specialized than the gynoecia of Butomaceae.     

STRUCTURE AND DEVELOPMENT OF THE PERIANTH IN DOWNINGIA BACIGALUPII

The structure and ontogeny of the calyx and corolla of Downingia bacigalupii Weiler (Campanulaceae; Lobelioideae) were investigated for the purpose of comparing perianth development with previous observations on the floral bract, as well as elucidating the mechanism of development of the zygomorphic, sympetalous corolla. Sepals are uni-traced with a palmate, reticulate venation. They have basal and apical hydathodes, as well as storage tracheids. Sepals show a reduction in size, venation and hydathode number when compared to the bract. The pentamerous, zygomorphic corolla is bilabiate, consisting of a three-lobed adaxial lip and a two-lobed abaxial lip connected by a short tubular region. The constituent petal lobes are also uni-traced and have a reticulate venation, resembling that of the sepal and bract, but lack storage tracheids and hydathodes. Sepals arise in an adaxial to abaxial succession and are initiated in the outer corpus layer of the floral apex. Expansion of the floral apex follows and is accompanied by the establishment of a second tunica layer. Sepals undergo apical, marginal, and intercalary growth accompanied by acropetal differentiation of procambium. The petals arise simultaneously and are initiated in the second tunica layer and the outer corpus cells. After initiation, the petals exhibit a period of apical and marginal growth followed by intercalary growth. Apical growth in petals is less protracted than in sepals, but plate meristem activity is more extensive. The free petal lobes become temporarily fused by an interlocking of marginal epidermal layers, but they separate at anthesis. Zonal growth beneath the originally free lobes forms the tube and lip regions of the sympetalous corolla. Zygomorphy is evident from the time of initiation of petals and is accentuated by later differential growth. Comparative observations of corolla ontogeny in autogamous species of Doumingia indicate that the reduced corollas in these taxa are derived by a simple process of neoteny.     

UNIDIRECTIONAL ORGAN INITIATION IN LEGUMINOUS FLOWERS

The order of initiation of floral organs is compared in several legumes. In Bauhinia fassoglensis, a caesalpinioid, the sepals are initiated helically, with the first one forming abaxially. In Genista tinctoria and Lupinus affinis (both papilionoids) the sepals are initiated unidirectionally, with the first forming on the abaxial side of the floral apex and subsequent sepals initiating laterally and then adaxially. All three taxa show unidirectional order of initiation for petals, first-whorl stamens, and second-whorl stamens. In each whorl, the first member or members form on the abaxial side, next to the subtending bract, then the lateral ones, and lastly the member(s) on the adaxial side, next to the axis. In Lupinus and Genista there are overlaps in time of initiation between organs in different whorls; for instance, the first stamens begin initiating before the last petals appear. Size differences among members of a whorl are evident in early stages, but may disappear after organogeny ceases, when the members become equal in size in each whorl. This precocious onset of dorsiventrality in floral development is viewed as a specialized feature.     

ORIGIN AND DEVELOPMENT OF THE TERMINAL CARPEL IN PSEUDOWINTERA TRAVERSII

Flowers of Pseudowintera traversii (Buchan.) Dandy possess a terminal unicarpellate gynoecium. The present study of carpel morphogenesis was initiated for the purposes of (1) providing additional developmental documentation of the occurrence of terminal carpels in the Winteraceae and (2) comparing the mode of initiation and development of the ascidiate terminal carpel of P. traversii with the essentially conduplicate terminal carpel of Drimys lanceolata. Following its axillary origin, the floral apex of P. traversii initiates 2–3 connate sepals, 5–6 petals, 4–15 stamens, and usually a single terminal carpel, in acropetal succession. Bicarpellate gynoecia may occur with a frequency of up to 15 % on a given plant. The floral apex is zonate and shows increased expression of its zonation during later stages of floral development. The terminal carpel is ascidiate from inception and originates as a cylindrical growth around the entire circumference of the floral apex; transformation of the floral meristem into a carpel primordium terminates apical growth of the floral axis. Carpel growth continues to be cylindrical and is mediated by a ring of marginal and submarginal initials at its summit. Earlier and more extensive division of initials and their derivatives on the dorsal rim causes the primordium to become canted adaxially, shifting the apical cleft to a subterminal adaxial position. Continued marginal meristematic activity results in closure of the cleft as well as elevation and elaboration of the stigmatic crests. Five to seven bitegmic ovules are initiated at the same time as crest elaboration and arise in two rows from the adaxial (laminar) position. Carpel maturation is signified by tannin deposition and oil cell differentiation, beginning at the base and proceeding acropetally; carpel margins bordering the cleft are the last to differentiate. Carpel procambialization is continuous and acropetal from inception, with the dorsal median bundle differentiating before the ventral strands. The significance of occasional bicarpellate flowers is discussed.     

COMPARATIVE ONTOGENY OF THE INFLORESCENCE AND FLOWER OF HAMAMELIS VIRGINIANA AND LOROPETALUM CHINENSE (HAMAMELIDACEAE)

A comparative developmental study of the inflorescence and flower of Hamamelis L. (4-merous) and Loropetalum (R. Br.) Oliv. (4–5 merous) was conducted to determine how development differs in these genera and between these genera and others of the family. Emphasis was placed on determining the types of floral appendages from which the similarly positioned nectaries of Hamamelis and sterile phyllomes of Loropetalum have evolved. In Hamamelis virginiana L. and H. mollis Oliv. initiation of whorls of floral appendages occurred centripetally. Nectary primordia arose adaxial to the petals soon after the initiation of stamen primordia and before initiation of carpel primordia. In Loropetalum chinense (R. Br.) Oliv. floral appendages did not arise centripetally. Petals and stamens first arose on the adaxial portion, and then on the abaxial portion of the floral apex. The sterile floral appendages (sterile phyllomes of uncertain homology) were initiated adaxial to the petals after all other whorls of floral appendages had become well developed. In all three species, two crescent shaped carpel primordia arose opposite each other and became closely appressed at their margins. Postgenital fusion followed and a falsely bilocular, bicarpellate ovary was formed. Ovule position and development are described. The nectaries of Hamamelis and sterile phyllomes of Loropetalum rarely develop as staminodia, suggesting a staminodial origin. However, these whorls arise at markedly different times and are therefore probably not derived from the same whorl of organs in a common progenitor. This hypothesis seems probable when one considers that the seemingly least specialized genus of the tribe, Maingaya, bears whorls of both staminodia and sterile phyllomes inside its whorl of stamens.     

The control of flower initiation by gibberellin in Helianthus annuus L. (sunflower), a non-photoperiodic plant

The involvement of gibberellins in the control of flowering of sunflower was studied by direct application of GA₃ to the apex of the plants, analysis of the endogenous levels of gibberellin-like substances at different plant ages, and indirectly by the application of paclobutrazol, an inhibitor of gibberellin synthesis. GA₃ speeded-up flower initiation and floral apex development. The time of GA₃ application was more critical than the amount of GA₃ applied. The endogenous levels of gibberellin-like compounds increased significantly by day 15 after sowing. The application of paclobutrazol markedly delayed floral initiation and this effect was also depedent on plant age. Both GA₃ and paclobutrazol had their greatest effects between 10 and 20 days after sowing suggesting that an increase in gibberellins in that time period plays a role in floral initiation.     

INFLORESCENCE AND FLOWER DEVELOPMENT IN THE PIPERACEAE III. FLORAL ONTOGENY OF PIPER

Floral development in Piper was compared between four-staminate species (P. aduncum and P. marginatum) and six-staminate species (P. amalago). All Piper species have a syncarpous gynoecium composed of three or four carpels. The floral apex is initiated by a periclinal division in the subsurface layer in the axil of a bract 40-55 μm high; initiation of the bracts occurs separately and considerably earlier. The floral primordium widens and the first pair of stamens are initiated at either side. The median anterior stamen forms next, and the median posterior later. This sequence is common to all species studied. In the six-staminate P. amalago, the last two stamens form simultaneously in lateral-anterior positions. The stamens hence arise as pairs, and symmetry is bilateral or dorsiventral. The three or four carpels arise simultaneously; they are soon elevated on a gynoecial ring by growth of the receptacle below the level of attachment of the carpels to produce a syncarpous gynoecium. The floral apex lastly produces the solitary basal ovule and is used up in its formation.     

CELL DIVISION STUDIES OF THE SHOOT APEX OF DATURA STRAMONIUM DURING TRANSITION TO FLOWERING

Seedlings of Datura stramonium L., although not photoperiodically sensitive, are useful for floral transition studies when raised in a growth chamber at a constant temperature of 25 C with a photoperiod of 8 hr of light (1,600-2,000 ft-c) and 16 hr of darkness. A terminal flower is formed after the seventh or eighth leaf primordium is produced. A constant rate of leaf initiation up to the time of flowering enables specific apical stages to be obtained and studied. Changes in the mitotic index, substantiated with calculated rates of cell division (measured by the accumulation of metaphases following treatment with colchicine) were studied in shoot apical zones during transition to flowering. Fluctuations in the mitotic index of each zone in the vegetative and transition apex with respect to apical stage as well as time of day were not statistically significant. The mitotic index of the summit zone of the vegetative apex was significantly lower than in the other zones whose mitotic indices were not significantly different from one another. During floral transition the mitotic index of the summit zone as well as the central zone (just below the summit zone) significantly increased while no significant changes were detected in the flank zones. It was shown that the mitotic index could be considered representative of the rates of cell division in Datura.     

TENDRILS OF PASSIFLORA FOETIDA: HISTOGENESIS AND MORPHOLOGY

Passiflora foetida bears an unbranched tendril, one or two laterally situated flowers, and one accessory vegetative bud in the axil of each leaf. The vegetative shoot apex has a single-layered tunica and an inner corpus. The degree of stratification in the peripheral meristem, the discreteness of the central meristem, and its centric and acentric position in the shoot apex are important plastochronic features. The procambium of the lateral leaf trace is close to the site of stipule initiation. The main axillary bud differentiates at the second node below the shoot apex. Adaxial to the bud 1–3 layers of cells form a shell-zone delimiting the bud meristem from the surrounding cells. A group of cells of the bud meristem adjacent to the axis later differentiates as an accessory bud. A second accessory bud also develops from the main bud opposite the previous one. A bud complex then consists of two laterally placed accessory bud primordia and a centrally-situated tendril bud primordium. The two accessory bud primordia differentiate into floral branches. During this development the initiation of a third vegetative accessory bud occurs on the axis just above the insertion of the tendril. This accessory bud develops into a vegetative branch and does not arise from the tissue of the tendril and adjacent two floral buds. The trace of the tendril bud consists of two procambial strands. There is a single strand for the floral branch trace. The tendril primordium grows by marked meristematic activity of its apical region and general intercalary growth.     

PATTERNS OF FLORAL DEVELOPMENT IN AGALINIS AND ALLIES (SCROPHULARIACEAE). II. FLORAL DEVELOPMENT OF AGALINIS DENSIFLORA

Initiation of floral primordia begins in Agalinis densiflora with production of two lateral adaxial calyx lobe primordia followed by a midadaxial primordium, and then primordia of two abaxial calyx lobes. Initiation of three abaxial corolla lobe primordia is succeeded by that of two stamen pairs and then by primordia of two adaxial corolla lobes. The primordium of the abaxial carpel appears before the adaxial one. Except for the calyx, initiation of primordia proceeds unidirectionally from the abaxial to the adaxial side of the floral apex. Zygomorphy in the calyx, corolla, and androecium is evident during initiation of primordia and is accentuated during organogenesis. The calyx undergoes comparatively rapid organogenesis, but the inner three floral series undergo a protracted period of organogenesis. The perianth series reach maturation prior to meiosis in the anthers. Maturation of the androecium and gynoecium are postmeiotic events.     

INFLORESCENCE AND FLOWER DEVELOPMENT IN THE PIPERACEAE. II. INFLORESCENCE DEVELOPMENT OF PIPER

The inflorescence development of three species of Piper (P. aduncum, P. amalago, and P. marginatum), representing Sections Artanthe and Ottonia, was studied. The spicate inflorescences contain hundreds or even thousands of flowers, depending on the species. Each flower has a tricarpellate syncarpous gynoecium and 4 to 6 free stamens, in the species studied. No sepals or petals are present. In P. marginatum the apical meristem of the inflorescence is zonate in configuration and is unusually elongate: up to 1,170 μm high and up to 480 μm wide during the most active period of organogenesis. Toward the time of apical cessation both height and diameter gradually diminish, leaving an apical residuum which may become an attenuate spine or may be cut off by an abscission zone just below the meristem. The active apex produces bract primordia; when each is 40–55 μm high, a floral apex is initiated in its axil. Both bract and floral apex are initiated by periclinal divisions in cells of the subsurface layer. The bracts undergo differentiation rather early, while the floral apices are still developing. The last-produced bracts near the tip of the inflorescence tend to be sterile.     

A morphological study of flower initiation and development in strawberry (Fragaria x ananassa) using cryo-scanning electron microscopy

The morphological changes in the apex of strawberry (Fragaria x ananassa) cv. Elsanta during flower initiation and early development were studied by means of apical dissections and cryo-scanning electron microscopy. Characteristic stages of development were recorded from the earliest discernible evidence of floral initiation until anthesis. The results are discussed in relation to previous studies of floral development in strawberry.     

The Growth of the Shoot Apex and the Apical Dome of Barley During Ear Initiation

The growth of the floral main shoot apex of spring barley wasstudied during the period of ear initiation (that is, from initiationof the collar primordium until maximum primordium number wasattained). While floral primordia were being initiated the relativelength growth rate of the shoot apex was low. After maximumprimordium number there was about a twofold increase in relativelength growth rate. Estimates of the volume, fresh and dry weightof the floral apex indicated that the relative weight growthrate was also low at first and increased after maximum primordiumnumber. The rates of growth and the size at initiation of thefloral primordia was affected by their position on the floralshoot apex. The relative volume growth rate increased acropetallyfrom the first initiated (collar) primordium. The collar wasthe smallest and each subsequently-initiated primordium increasedin length. The diameter of the newly-initiated primordium alsoincreased until more than half the primordia had been initiatedand then it declined. The apical dome increased in both lengthand diameter and both were at a maximum at the time of the double-ridgestage and then both measurements declined. Length and diameterwere at a minimum at maximum primordium number. Subsequentlythere was an increase in the length of the dome, after whichboth the dome and some of the last formed, distal primordiadied. The period of spikelet initiation therefore is a stage duringwhich the relative growth rate of the floral shoot apex is low,there are changes in the size of the dome and the primordiashow a progression of increasing relative growth rates acropetallyalong the shoot apex. These changes produce the embryo ear inwhich the most advanced spikelets are in the lower mid-partof the ear. Changes in size of the apical dome prior to maximumprimordium number may be related to the subsequent death ofspikelet primordia and therefore also to grain number in themature ear.     

A SCANNING ELECTRON MICROSCOPIC STUDY ON THE INITIATION AND DEVELOPMENT OF FLORAL ORGANS OF BRASSICA NAPUS (CV. WESTAR)

The initiation and development of the floral organs of Brassica napus L. (cv. Westar) were examined using the scanning electron microscope. After transition of the vegetative apex into an inflorescence apex, flower primordia were initiated in a helical phyllotactic pattern. The sequence of initiation of the floral organs in a flower bud was that of sepals, stamens, petals and gynoecium. Of the four sepal primordia, the abaxial was initiated first, followed by the two lateral and finally the adaxial primordium. The four long stamens were initiated simultaneously in positions alternating with the sepals. The two short stamens were initiated basipetal to and outside the long stamens, and opposite the lateral sepals. The petals arose on either side of the two short stamens and the gynoecium was produced from the remainder of the apex. During development, the sepal primordia curved sharply at the tips and tightly enclosed the other organs. Stamen primordia developed tetralobed anthers at an early stage while filament elongation occurred just prior to anthesis. A unique pattern of bulbous cells was present on the abaxial surface of the anther. Growth of petal primordia lagged relative to the other floral organs but expansion was rapid prior to anthesis. The gynoecium primordium was characterized by an invagination early in development. At maturity, there was differentiation of a papillate stigma, an elongated style and a long ovary marked externally by sutures and divided internally by a septum. Distinct patterns of cuticular thickenings were observed on the abaxial and adaxial surfaces of the petals and stamens and on the surface of the style. The patterns were less obvious on the sepals and ovary. Stomata were present on both surfaces of the mature sepals, on the style and restricted areas on the abaxial surface of the anthers and nectaries but were absent from the petals, the adaxial surface of the stamens and the ovary. No hairs were present on any of the floral organs.