The inflorescence structure of Kummerowia (Leguminosae)

Inflorescences of Kummerowia are compound and the component axes appear to terminate in a flower. In order to clarify whether or not the flower is truly terminal, inflorescences of Kummerowia were studied organographically, ontogenetically and anatomically. Four inflorescence phyllomes are usually produced immediately below the seemingly terminal flower and appear to be borne on the same axis. The second phyllome subsequent to the lowest one is located at right angles to the lowest one, and the third and fourth ones located opposite each other and at right angles to the second. The lowest phyllome is sometimes undeveloped in K.stipulacea. Ontogenetic observation revealed the presence of two abortive apiceS. Anatomical observation revealed that these two abortive apices remain rudimentary in the flowering stage. On the basis of the arrangement of these phyllomes and the presence of the remnants of apices, the structure of the component inflorescence axis in Kummerowia is interpreted as follows: the component axis branches off a lateral axis, which is reduced entirely in length, from the axil of the lowest phyllome, and terminates in an abortive apex; the lateral axis in turn branches off one lateral axis of the next order, which is also reduced in length, from the axil of the second phyllome and terminates in an abortive apex; the lateral axis of the next order produces the third and fourth phyllomes and is terminated by a flower. The flower, which seems to terminate the component axis, is therefore axillary in origin. The axillary branch of the lowest phyllomes occasionally bears two lateral flowers. The branching system of the inflorescence of Kummerowia is identical with that of an inflorescence of Lespedeza cuneata. Kummerowia and Lespedeza are continuous in characteristics of the inflorescence, indicating the relationship between the inflorescence of Kummerowia and the pseudoraceme of Lespedeza.     

Organographic and ontogenetic studies on the inflorescence ofLespedeza cuneata (Dum.-Cours.) G. Don (Leguminosae)

Structure of inflorescence and its variation were organographically and ontogenetically studied inLespedeza cuneata (Dum.-Cours.) G. Don. An axillary inflorescence of the species forms a compound inflorescence which is composed of three or four component inflorescences. Each component inflorescence bears four (rarely six), three, two, or one flowers. Based on the arrangement of inflorescence phyllomes, the component inflorescence with four flowers is interpreted as a pseudoraceme bearing two shortened lateral shoots (partial inflorescences) each of which has two flowers. The component inflorescence with one flower appears to be terminated by the flower and to compose the cyme. Organographic observations revealed that the terminally located flower is not truly terminal, but axillary in origin. Ontogenetic observations showed that the apices of component inflorescence and partial inflorescence exist in early developmental stages in spite of variation in the form of component inflorescence. The terminally located flower in the cyme-like inflorescence was thus demonstrated to be laterally borne on the partial inflorescence axis. The component inflorescence composing the cyme-like one inL. cuneata is a reduced form in the number of partial inflorescences and of flowers from the pseudoraceme. The cyme-like inflorescence inL. cuneata resembles the inflorescence ofKummerowia.     

SYMMETRY AND DEVELOPMENT OF BUTOMUS UMBELLATUS (BUTOMACEAE) AND LIMNOCHARIS FLAVA (LIMNOCHARITACEAE)

The prostrate rhizome of Butomus umbellatus produces branch primordia of two sorts, inflorescence primordia and nonprecocious vegetative lateral buds. The inflorescence primordia form precociously by the bifurcation of the apical meristem of the rhizome, whereas the non-precocious vegetative buds are formed away from the apical meristem. The rhizome normally produces a branch in the axial of each foliage leaf. However, it is unclear whether the rhizome is a monopodial or a sympodial structure. Lateral buds are produced on the inflorescence of B. umbellatus either by the bifurcation or trifurcation of apical meristems. The inflorescence consists of monochasial units as well as units of greater complexity, and certain of the flower buds lack subtending bracts. The upright vegetative axis of Limnocharis flava has sympodial growth and produces evicted branch primordia solely by meristematic bifurcation. Only certain leaves of the axis are associated with evicted branch primordia and each such primordium gives rise to an inflorescence. The flowers of L. flava are borne in a cincinnus and, although the inflorescence is simpler than that of Butomus umbellatus, the two inflorescences appear to conform to a fundamental body plan. The ultimate bud on the inflorescence of Limnocharis flava always forms a vegetative shoot, and the inflorescence may also produce supernumerary vegetative buds. Butomus umbellatus and Limnocharis flava exhibit a high degree of mirror image symmetry.     

Pseudoracemes in papilionoid legumes: their nature, development, and variation

Pseudoracemes in papilionoid legumes: their nature, development, and variation. Cymelike partial inflorescences called fascicles have been reported in the inflorescences of several papilionoid tribes. The total inflorescence is termed a ‘pseudoraceme’ because of the multiple flowers in each bract axil. Pseudoraceme development has been studied in 22 taxa in five papilionoid tribes (Abreae, Desmodieae, Millcttieae, Phaseoleae and Psoraleeae). Two to twelve flowers occur per bract axil among various taxa, with three the most common number.Pongamia pinnata and Clitoris fairchildiana have only two flowers per axil; Vigna radiata, Phaseolus vulgaris, and Apios americana have four to five commonly, and Dioclea aff.ucayalina and Abrus precalorius have up to 12. The ‘fascicle’ usually consists of a triad of three flowers; each triad resembles a dichasial cyme in that the middle flower appears terminal. The middle flower however is subtended by a bract on the abaxial side, so that the middle flower is technically lateral. When the first-order axis elongates, each triad may either remain intact or be separated by axis intervalS. Many variations on the basic triad pattern occur in the species studied: 1.one or two flowers may develop while others that are initiated remain suppressed; 2. Additional flowers may be produced that replicate the first triad; 3. Additional flowers may form medianly only, on the abaxial side. The second-order inflorescence axis which has produced the three flowers persists to produce more flowers in replication of the triad pattern in several taxa (Apios americana, Vigna radiata, Phaseolus vulgaris, and Dioclea aff.ucayalina). In Butea monosperma the second-order inflorescence apex produces subsequent flowers (after the triad) in a helix. In Erylhrina perrieri, there is no indication of a persistent second-order inflorescence apex after the central flower; such a condition could be interpreted as a cyme, except for the abaxial subtending bract. The triad in Psoralea pinnata is a true cyme; the middle flower lacks a subtending bract other than that subtending the entire fascicle. Developmentally, the difference between a cyme and an early-determinate raceme (as in the triad type of pseudoraceme) is rather slight. Comparison of the types of inflorescences described here may indicate how the transition may have occurred between racemes and cymes in the evolution of legumes.     

INFLORESCENCE AND FLOWER STRUCTURE IN NYPA FRUTICANS (PALMAE)

Details of organogenesis, anatomy, and some aspects of histogenesis are described for the inflorescence units and flowers of the mangrove palm, Nypa fruticans. The genus is of special interest in evolutionary studies because of its disjunct morphology and substantial fossil record. The inflorescence is an erect monopodial axis bearing 7–9 lateral branches and ending in a pistillate head. The lowest of the lateral branches bears up to six orders of branches, the next ones progressively fewer, and the uppermost is usually unbranched. Lateral branches of all orders end in thick spicate, staminate rachillae. The rachillae and the pistillate head consist of spirally inserted sessile flowers, each borne in the axil of a bract. Staminate and pistillate flowers are similar in structure. Both have three separate sepals and three separate petals, which are loosely closed in bud. Staminate flowers have no pistillodes; nor are there any staminodes in the pistillate flower. The androecium consists of a stalk bearing three anthers distally and is shown to represent three stamens with filaments congenitally fused and anthers connate by the ventral faces of the connectives. The pistillate flower has three separate carpels, which expand rapidly so that by anthesis they much exceed the perianth. Each carpel is cupulate in shape, with a two-crested distal opening, and receives ca. 150 vascular bundles, many of which may branch dichotomously. No dorsal or ventral bundles can be definitely distinguished, but a ventrally open ring of 10–12 bundles surrounding the locule matures first. Allometric growth clearly accounts for much of the morphological disjunction in the reproductive organs of Nypa contrasted with those of other palms. Resemblances to coryphoid, ceroxyloid, arecoid, and cocosoid palms are indicated by these studies. Different combinations of characters and several distinctive features justify a separate major taxonomic category for this genus within the Palmae.     

THE ANATOMY OF THE PISTILLATE INFLORESCENCE AND FLOWER OF CASUARINA VERTICILLATA LAMARCK (CASUARINACEAE)

The pistillate inflorescence of Casuarina verticillata is described as consisting of a primary axis bearing whorls of bracts with a cymule in the axil of each bract of the more central whorls. Each cymule consists of an atepallate, two-carpellate, syncarpous floret and two, lateral, once-lobed bracteoles. A “peripheral intercalary” meristem, in which divisions are primarily periclinal, forms a meshwork beneath the bracts from early development and moves the connate bracts centrifugally around the cymules and extends and binds the bracts, and to some extent the bracteoles, of the fertile part of the inflorescence together. Each bract receives a single trace; each cymule receives two traces. Each bundle extension of a cymule trace supplies: 1) a branch which joins its counterpart to become the anterior common carpellary bundle; 2) a second branch which joins its counterpart to become the posterior common carpellary bundle; and 3) a central branch which supplies a lateral bracteole. Within each floret, each common carpellary bundle provides a dorsal carpellary bundle, two ventral carpellary bundles (fertile anterior carpel) or one common ventral bundle (sterile posterior carpel). The ventral bundle-supplies join and form a single placental bundle which lies in the gynoecial septum, and which, in turn, supplies the two ovules in the anterior carpel. Whether the inflorescence is a simple racemose or a condensed cymose type cannot be determined from this species alone. The function of the sclerenchymatous, enclosing bracteoles and connate bracts is discussed.     

BIFURCATION OF THE STEM APEX IN ASCLEPIAS SYRIACA

In Asclepias syriaca the overall inflorescence is an anthoclad in which the peduncles are non-axillary, each occurring about 60° away from the axil of a leaf. Ontogenetically, a peduncle is initiated when the stem apex expands laterally and bifurcates into separate apices, neither of which is subtended by any type of organ. One of the two apices continues as the functional apex of the stem (bifurcating again at each subsequent node), and the other functions as the apex of the peduncle. The peduncle first produces a bract and, then, a pedicel in the axil of the bract. Subsequent pedicels are each axillary to separate bracts. The pedicels, therefore, can be interpreted as ordinary lateral branches. However, because the bifurcations of the stem apex are not associated with subtending organs, the branching of the stem does not conform to expected monopodial or sympodial systems in the angiosperms. This suggests the possibility that each bifurcation of the stem apex is a true dichotomy. The anthoclad axis, thus, is a series of dichotomies. Although such a series may have been phylogenetically derived from a monopodial or sympodial ancestor, it is also possible that it may have been retained from a primitive, dichotomizing inflorescence.     

FLORAL DEVELOPMENT IN MYRISTICA (MYRISTICACEAE)

Myristica fragrans and M. malabarica are dioecious. Both staminate and pistillate plants produce axillary flowering structures. Each pistillate flower is solitary, borne terminally on a short, second-order shoot that bears a pair of ephemeral bracts. Each staminate inflorescence similarly produces a terminal flower and, usually, a third-order, racemose axis in the axil of each pair of bracts. Each flower on these indeterminate axes is in the axil of a bract. On the abaxial side immediately below the perianth, each flower has a bracteole, which is produced by the floral apex. Three tepal primordia are initiated on the margins of the floral apex in an acyclic pattern. Subsequent intercalary growth produces a perianth tube. Alternate with the tepals, three anther primordia arise on the margins of a broadened floral apex in an acyclic or helical pattern. Usually two more anther primordia arise adjacent to each of the first three primordia, producing a total of nine primordia. At this stage the floral apex begins to lose its meristematic appearance, but the residuum persists. Intercalary growth below the floral apex produces a columnar receptacle. The anther primordia remain adnate to the receptacle and grow longitudinally as the receptacle elongates. Each primordium develops into an anther with two pairs of septate, elongate microsporangia. In pistillate flowers, a carpel primordium encircles the floral apex eventually producing an ascidiate carpel with a cleft on the oblique apex and upper adaxial wall. The floral ontogeny supports the morphological interpretation of myristicaceous flowers as trimerous with either four-sporangiate anthers or monocarpellate pistils.     

Pedicel development in Arabidopsis thaliana: contribution of vascular positioning and the role of the BREVIPEDICELLUS and ERECTA genes

Although the regulation of Arabidopsis floral meristem patterning and determinacy has been studied in detail, very little is known about the genetic mechanisms directing development of the pedicel, the short stem linking the flower to the inflorescence axis. Here, we provide evidence that the pedicel consists of a proximal portion derived from the young flower primordium, and a bulged distal region that emerges from tissue at the bases of sepals in the floral bud. Distal pedicel growth is controlled by the KNOTTED1-like homeobox gene BREVIPEDICELLUS (BP), as 35S::BP plants show excessive proliferation of pedicel tissue, while loss of BP conditions a radial constriction around the distal pedicel circumference. Mutant radial constrictions project proximally along abaxial and lateral sides of pedicels, leading to occasional downward bending at the distal pedicel. This effect is severely enhanced in a loss-of-function erecta (er) background, resulting in radially constricted tissue along the entire abaxial side of pedicels and downward-oriented flowers and fruit. Analysis of pedicel vascular patterns revealed biasing of vasculature towards the abaxial side, consistent with a role for BP and ER in regulating a vascular-borne growth inhibitory signal. BP expression in a reporter line marked boundaries between the inflorescence stem and lateral organs and the receptacle and floral organs. This boundary expression appears to be important to prevent homeotic displacement of node and lateral organ fates into underlying stem tissue. To investigate interactions between pedicel and flower development, we crossed bp er into various floral mutant backgrounds. Formation of laterally-oriented bends in bp lfy er pedicels paralleled phyllotaxy changes, consistent with a model where the architecture of mutant stems is controlled by both organ positioning and vasculature patterns. Collectively, our results indicate that the BP gene acts in Arabidopsis stems to confer a growth-competent state that counteracts lateral-organ associated asymmetries and effectively radializes internode and pedicel growth and differentiation patterns.     

AXILLARY AND DICHOTOMOUS BRANCHING IN THE PALM CHAMAEDOREA

In both Chamaedorea seifrizii Burret and C. cataractarum Martius each adult foliage leaf subtends one axillary bud. The proximal buds in C. seifrizii are always vegetative, producing branches (= new shoots or suckers); and the distal buds on a shoot are always reproductive, producing inflorescences. The prophyll and first few scale leaves of a vegetative branch lack buds. Transitional leaves subtend vegetative buds and adult leaves subtend reproductive buds. Both types of buds are first initiated in the axil of the second or third leaf primordia from the apex, P2 or P3. Later development of both types of bud tends to be more on the adaxial surface of the subtending leaf base than on the shoot axis. Axillary buds of C. cataractarum are similarly initiated in the axil of P2 or P3 and also have an insertion that is more foliar than cauline. However, all buds develop as inflorescences. Vegetative branches arise irregularly by a division of the apex within an enclosing leaf (= P1). A typical inflorescence bud is initiated in the axil of the enclosing leaf when it is in the position of P2 and when each new branch has initiated its own P1. No scale leaves are produced by either branch and the morphological relationship among branches and the enclosing leaf varies. Often the branches are unequal and the enclosing leaf is fasciated. The vegetative branching in C. cataractarum is considered to be developmentally a true dichotomy and is compared with other examples of dichotomous (= terminal) branching in the Angiospermae.     

Inflorescence development in a perennial teosinte: Zea perennis (Poaceae)

The ontogeny of tassels and ears in a perennial Mexican teosinte, Zea perennis (Hitchc.) Reeves and Mangelsdorf, was examined using scanning electron microscopy and light microscopy. Ear development follows a pattern previously described for two annual teosintes, Z. mays subsp. mexicana and Z. mays subsp. parviglumis var. parviglumis (race Balsas), and for the bisexual mixed inflorescence in a diploperennial teosinte, Z. diploperennis; it differs from that described for the ear of Z. diploperennis plants grown at the latitudes of Iowa and Wisconsin. Common bud primordia of the ear are initiated in the axil of distichously arranged bracts along the ear axis. These common primordia bifurcate to form paired pedicellate and sessile spikelet primordia. Development of the pedicellate spikelets in the ear is arrested leaving the sessile spikelets, along with the adjoining rachis segment, to form solitary grains enclosed within cupulate fruitcases. The organogenesis of the central spike of the tassel is similar to that previously described in other Zea taxa. This developmental study supports the hypothesis that both femaleness and maleness are derived from and expressed on a common background; it is consistent with the view that the maize ear was derived from the central spike of a male inflorescence terminating a primary branch of the main axis of the inflorescence.     

DEVELOPMENTAL STUDIES IN PTYCHOSPERMA (PALMAE). I. THE INFLORESCENCE AND THE FLOWER CLUSTER

This paper describes inflorescence structure, including organogenesis of the panicle and flower clusters and vasculature of flowering branches, for two species of Ptychosperma, a genus of arecoid palms. The inflorescence is an infrafoliar panicle with up to four orders of branches in a spirodistichous arrangement conforming to an irregular one-half phyllotaxy. The primordium of the inflorescence is crescentic and the apex has two tunica layers, a group of central cells, and a rib meristem. The distal flower-bearing parts or rachillae of all branches develop acropetally early in ontogeny and are vertically oriented in the bud. Although these rachillae terminate branches of different sizes and orders, they are similar in size and in number of flower clusters produced. Internodes and lower parts of branches develop later. Bracts of four types are produced: a prophyll and empty peduncular bract, bracts which subtend lateral branches, bracts subtending triads, and floral bracteoles. The prophyll and peduncular bracts are tubular and completely closed around all branches until about three months before the flowers reach anthesis. Bracts subtending lateral branches and those that subtend triads enlarge by small amounts of apical, adaxial, and marginal growth to cover subtended apices during early ontogeny, but are small to absent at maturity. Flower clusters are triads of two lateral staminate and a central pistillate flower. Organogenesis indicates that the triad is a sympodial unit. Flowers develop successively, each floral apex bearing a bracteole that subtends the next flower. The vasculature of the inflorescence may be divided into two systems. Bundles of the main axis extend acropetally into the vertically oriented branches as they are initiated and form a central cylinder of larger bundles in each branch. Flower clusters are supplied by a peripheral system of smaller bundles that develop later in relation to the developing floral organs. Bundles of the peripheral system branch frequently, but branching levels are irregular. The irregular branching of peripheral bundles appears related to the phyllotaxy of the flower clusters and the random right or left position of the first flower of the triad. The level of branching of a bundle may depend on the position of a floral primordium with respect to an existing procambial strand. Three (-4) bundles supply each staminate flower and six (-10) the pistillate flower. The histologically specialized inflorescence has stomata and contains abundant starch. Tannins and raphides, spherical silica bodies, and various forms of sclerenchyma appear in sequence and apparently provide support and protection during the long exposure of the branches.     

The branching of the inflorescence and vegetative shoot and taxonomy of the genusKummerowia (Leguminosae)

A study of the branching of the inflorescence and the vegetative shoot of the genusKummerowia, consisting ofK. stipulacea (Maxim.) Makino andK. striata (Thunb.) Schindler, has led to the following conclusions: (1) the inflorescences of both species are reduced compound cymes, (2) the branching system of the inflorescence ofKummerowia is not clearly different from that of the vegetative shoot and there are some transitional forms between both systems, and (3) the inflorescence ofKummerowia is different from the racemose inflorescences ofLespedeza andCampylotropis. Based on the differences found in the branching system of the inflorescence,Kummerowia is distinctly separated fromLespedeza andCampylotropis and is more correctly treated as a distinct genus from the latter two.     

Differential cell enlargement and its possible implication for resupination in Lemboglossum bictoniense (Orchidaceae)

Changes in the structural features of cell populations in the pedicel of Lemboglossum bictoniense (Bateman ex. Lindley) Halbinger were examined by means of light microscopy in relation to resupination, a twisting of the pedicel through 180^o prior to flower opening. Serial sections in transverse and longitudinal planes were taken from pre-resupinate and fully resupinate pedicels of flowers from a single inflorescence, and comparisons made between the tissues. The pedicel is a prismatic cylinder flattened on three sides, producing three distinct ribS. Each rib contains one central vascular bundle enclosed by cortical parenchyma. Intervening cortical parenchyma forms flanks external to a central core of three vascular bundles, each of which is split into three distinct traces at this level. Resupination is accompanied by axial and radial expansion of cortical parenchyma. Specialized raphide-bearing cells in the cortex expand axially doubling their length in the ground parenchyma. These raphide cells are localized in the rib cortex, and their expansion is reflected in greater elongation of the ribs relative to flank areas. The extra rib length is accommodated by a lateral displacement (twisting) of the ribs around the central axis of the pedicel. Tissue distortion is reduced by cell division, expansion of intercellular spaces and a radial contraction of pith parenchyma. Raphide cell elongation could be a contributing factor in pedicel twisting. The direction of resupination may be controlled by the organization of these cells into arcs on one or other side of the rib vascular bundle.     

THE ALLIUM INFLORESCENCE: SOME SPECIES OF THE SECTION MOLIUM

Mann , Louis K. (U. California, Davis.) The Allium inflorescence: some species of the section Molium. Amer. Jour. Bot. 46(10): 730–739. Illus. 1959.—The inflorescence is described for Allium neapolitanum, A. roseum, A. hirsutum, A. subhirsutum, A. zebdanense and A. erdelii, species of Molium, a Mediterranean section of the genus. Inflorescence structure is similar among these 6 species. The single spathe appears to consist of 4 coalesced bracts, each of which bears in its axil a bostryx (helicoid cyme) of 3–7 flowers. Central to these 4 peripheral bostryxes are several smaller ones which differentiate later and decrease in flower number toward the inflorescence center. Bracts and bracteoles (prophylls) are generally absent within the spathe. The inflorescence is not radially symmetrical and the bostryx on the side opposite the uppermost foliage leaf differentiates and develops first. Among the peripheral bostryxes there is a definite sequence of development and certain regularities of coiling (clockwise vs. counterclockwise). Within each bostryx the flowers open in a strict sequence from oldest to youngest; among the bostryxes, the 4 peripheral ones flower first, usually starting with the first bostryx to be differentiated. The central bostryxes flower last.     

Racemose inflorescences of monocots: structural and morphogenetic interaction at the flower/inflorescence level

Background

Understanding and modelling early events of floral meristem patterning and floral development requires consideration of positional information regarding the organs surrounding the floral meristem, such as the flower-subtending bracts (FSBs) and floral prophylls (bracteoles). In common with models of regulation of floral patterning, the simplest models of phyllotaxy consider only unbranched uniaxial systems. Racemose inflorescences and thyrses offer a useful model system for investigating morphogenetic interactions between organs belonging to different axes.

Scope

This review considers (1) racemose inflorescences of early-divergent and lilioid monocots and their possible relationship with other inflorescence types, (2) hypotheses on the morphogenetic significance of phyllomes surrounding developing flowers, (3) patterns of FSB reduction and (4) vascular patterns in the primary inflorescence axis and lateral pedicels.

Conclusions

Racemose (partial) inflorescences represent the plesiomorphic condition in monocots. The presence or absence of a terminal flower or flower-like structure is labile among early-divergent monocots. In some Alismatales, a few-flowered racemose inflorescence can be entirely transformed into a terminal ‘flower’. The presence or absence and position of additional phyllomes on the lateral pedicels represent important taxonomic markers and key features in regulation of flower patterning. Racemose inflorescences with a single floral prophyll are closely related to thyrses. Floral patterning is either unidirectional or simultaneous in species that lack a floral prophyll or possess a single adaxial floral prophyll and usually spiral in the outer perianth whorl in species with a transversely oriented floral prophyll. Inhibitory fields of surrounding phyllomes are relevant but insufficient to explain these patterns; other important factors are meristem space economy and/or the inhibitory activity of the primary inflorescence axis. Two patterns of FSB reduction exist in basal monocots: (1) complete FSB suppression (cryptic flower-subtending bract) and (2) formation of a ‘hybrid’ organ by overlap of the developmental programmes of the FSB and the first abaxial organ formed on the floral pedicel. FSB reduction affects patterns of interaction between the conductive systems of the flower and the primary inflorescence axis.     

Development of the cymose inflorescence, cupulum and flower of Psoralea pinnata (Leguminosae: Papilionoideae: Psoraleeae)

The inflorescence of Psoralea pinnata sensu lato is composed of dichasial cymes of three to seven flowers in each bract axil. However, the main inflorescence terminal is indeterminate. Cymes are very unusual among legumes, occurring in perhaps six or seven genera. The 'cupulum' is a unique structure found only in Psoralea among legumes. While highly variable in form, it serves as a protective structure around the calyx during development. Developmentally the cupulum results from fusion by intercalary growth of three to four successive bracts on the pedicel. Paired bracteoles are also produced above the cupulum and below the calyx, but they are very reduced and easily overlooked. Their presence is evidence that the cupulum is not part of the flower proper. Organogeny in P. pinnata is unidirectional in each floral whorl, starting on the abaxia! side, except for a minor exception in precocity of the vexillary (adaxial) stamen arising with the two lateral stamens of the same inner whorl. There is no overlap between whorls. The carpel is initiated early, during or just after petal initiation and before stamen initiation.     

Contributo preliminare alla sistematica di Chamaecytisus hirsutus e Chamaecytisus supinus

Abstract

Chamaecytisus hirsutus and C. supinus: a preliminary report. – Chamaecytisus hirsutus (L.) Link and C. supinus (L.) Link have been described as twostrictly related species, which differ mainly in the form of inflorescence: C. hirsutus has lateral flowers, C. supinus has terminal flowers. Besides, most Floras provide a set of additional differential characters that should permit to di-C. hirsutus and C. supinus.

The author analyses such differential characters and demonstrates that all of them are inconsistent: therefore the inflorescence seems to be the only difference between C. hirsutus and C. supinus.

The inflorescence itself, however, is not a constant character: indeed, it is known that C. supinus may develop vernal latera flowers besides the normal aestival terminal ones.

The geographic distributions of the two inflorescence types are accurately examined (a report of the distributions is given, a list of herbarium specimens is presented in appendix, a point distribution map of the two types is given in figs. 1 and 2); the only differences are the following ones: plants with flowers in leafy racemes (usually identified as C. hirsutus) seem to be absent from Spain and from Southern Poland, and to be unfrequent in Central and Western France; instead, plants with flowers in heads (usually identified as C. supinus) are very unfrequent in the Southern Balcan Peninsula, and are absent from Southern Greece and the Italian Peninsula.

After a discussion of the biological significance of the capitate and lateral inflorescence, and on the basis of in vivo observations, the author argues that probably the same taxonomic unit is present in the whole area, showing some differences in its flowering behaviour; in the largest part of the areal – including the center of distribution of the species – most individuals flower twice, and therefore have been recorded as two different species; a trend toward the capitate inflorescence is remarkable in the North and in the West; instead, in the South and the East the trend is toward lateral flowers (fig. 3).

Further biometrical and biochemical studies on the species are now in progress; more observations in field in different parts of Europe are necessary in order to get conclusive evidence of the identity of these two so-called «species».     

不同生境对蝴蝶花花部与果实特征的影响

通过对毛竹林(Bamboo forest,BF)与林缘旷地(Open area of forest edge,OAFE)两类生境蝴蝶花自然种群花部与果实(种子)特征及降雨干扰影响的研究,探讨不同生境中蝴蝶花花部特征适应性及有性各组分的差异。结果表明:(1)竹林生境相对于林缘旷地生境,蝴蝶花单花花冠的长、宽较大,子房、花部(除花柄)及单花总生物量较小,比花柄长较大;两类生境蝴蝶花花柄生物量与子房生物量呈正相关(P0.05),协方差分析表明,两类生境该直线回归的总体斜率间(F=18.420,P0.001)及总体截距间(F=3791.7,P0.001)均具有显著差异,竹林生境花柄生物量随子房生物量增大而增大的程度更强。竹林生境的蝴蝶花侧花花冠长与宽最高,竹林生境顶花次之,林缘旷地顶花与林缘旷地侧花最低;花部(除花柄)与全花重都表现为林缘旷地侧花最高,林缘旷地顶花次之,竹林侧花与竹林顶花最低。比花柄长随竹林侧花与竹林顶花-林缘旷地侧花-林缘旷地顶花依次降低;竹林顶花的花柄比率最高,竹林侧花与林缘旷地侧花最低。(2)林缘旷地生境中蝴蝶花的每花序花数、花序结果百分率、单花结果百分率、每结果花序果实数、每结果花序果实重与种子重及花期内每花序掉落花数都高于竹林生境。(3)林缘旷地生境大雨干扰的4个时段花朵掉落数显著高于竹林环境(P0.01)。不同生境花部形态结构特征表明其自身的生境适应性,林缘旷地生境蝴蝶花为抵御干扰及为获得有性繁殖成功,有性组分的投入更高。