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.     

MORPHOLOGY,EVOLUTION, AND TAXONOMIC SIGNIFICANCE OF THE INFLORESCENCE IN CORDYLANTHUS (SCROPHULARIACEAE)

The genus Cordyhmthus has considerable diversity in its inflorescences while the other genera of tribe Rhinantheae (Scrophulariaceae) uniformly have racemes or spikes. Four distinct inflorescence types are recognized and their homologies and evolutionary history are postulated. Thus it is suggested that the basic florescence type, the elongated spike (Type I), has undergone evolutionary reduction to a few-flowered spike and ultimately to a single-flowered florescence (Type II). Further evolution involving processes of compaction and clustering of the single-flowered florescences has resulted in glomerulate clusters (Type III) and spiciform clusters (Type IV). Knowledge of inflorescence homologies and distribution of the four inflorescence types in the genus has been of considerable aid in formulating a new infrageneric classification. Using evidence primarily from inflorescence, floral, and seed morphology, as well as from geographical distribution and ecology, a classification is proposed establishing three subgenera, namely subg. Dicranostegia, subg. Hemistegia, and subg. Cordylanthus, the last with three sections, sect. Cordylanthus, sect. Anisocheila, and sect. Ramosi.     

STUDIES ON THE ONTOGENY OF THE DWARF MISTLETOES,ARCEUTHOBIUM. III. DEVELOPMENT OF THE INFLORESCENCE

In vascular plants, the apical meristem of the shoot normally represents a continuation of growth in the apical meristem of the embryo itself. This is not the case in Arceuthobium. Here the shoot apex of the embryo is rudimentary and eventually dies after infection of the host occurs. The inflorescence of Arceuthobium is, therefore, an adventitious structure originating in the endophytic system rather than from the shoot apex of the seedling. Inflorescence buds arise in either of 2 ways. In some species (A. douglasii and A. americanum), buds first appear as small meristematic protuberances on the outer surface of cortical strands. In other species (A. campylopodum), the buds arise at the ends of short branches. The former, or diffuse, type gives rise to inflorescences along the entire surface of the host branch; in the latter, or condensed, type inflorescences are formed in clusters. Early ontogeny of the inflorescence apex of both types is described. Studies of subsequent growth of the inflorescence apex show 5 well-defined plastochronic stages: (1) maximal area stage; (2) minimal area stage; (3) early post-minimal stage; (4) late post-minimal stage; and (5) pre-maximal stage.     

DEVELOPMENT OF THE EPIPHYLLOUS INFLORESCENCE OF HELWINGIA JAPONICA (HELWINGIACEAE)

The inflorescence of Helwingia japonica (Thunb.) Dietr. is initiated adjacent to the leaf axil on the adaxial side of the base of a leaf primordium during its second plastochron. The inflorescence which develops from the resulting primordium comes to be situated on the midrib of the mature fertile leaf, through the action of a basal, intercalary meristem. In fertile leaves this meristem develops beneath, as well as above, the insertion of the inflorescence primordium on the leaf primordium. The same meristem is present in sterile leaves as well. A separate, adaxial vascular bundle departs from the leaf trace in the base of the petiole and leads to the inflorescence, in the mature fertile leaf. This adaxial vascular bundle is absent in sterile leaves. It is argued that the vascular anatomy does not conclusively confirm the hypothesis that the epiphyllous inflorescence is the congenital fusion product of a leaf and an axillary inflorescence. Instead, it is suggested that the interplay of changes in the position of primordium initiation, and intercalary growth, offers an ontogenetic explanation of the situation, which in turn may be related to the phylogeny of the species in question. It appears to be misguided and futile to look for homologies (i.e., 1:1 correspondences) between fertile and sterile leaves, since 1:1 correspondences do not exist in this case.     

EVOLUTIONARY SIGNIFICANCE OF THE LOSS OF THE CHLOROPLAST-DNA INVERTED REPEAT IN THE LEGUMINOSAE SUBFAMILY PAPILIONOIDEAE

The distribution of a rare chloroplast-DNA structural mutation, the loss of a large inverted repeat, has been determined for 95 species representing 77 genera and 25 of the 31 tribes in the legume subfamily Papilionoideae. This mutation, which is regarded as a derived feature of singular origin within the subfamily, marks a group comprising six temperate tribes, the Galegeae, Hedysareae, Carmichaelieae, Vicieae, Cicereae, and Trifolieae, an assemblage traditionally considered to be monophyletic. This mutation also occurs in the chloroplast genome of Wisteria, a member of the tropical tribe Millettieae whose other members so far surveyed lack the mutation. These new DNA data, together with traditional evidence, support the hypothesis that Wisteria is an unspecialized member of a lineage that gave rise to the temperate tribes marked by the chloroplast-DNA mutation; the probable paraphylesis of Millettieae is revealed. Two other tribes, Loteae and Coronilleae (traditionally regarded as a derived element of the aforesaid temperate tribes) do not possess this chloroplast-DNA structural mutation and, therefore, presumably represent a distinct temperate lineage. This hypothesis is supported by additional evidence from pollen, inflorescence, and root-nodule morphology that suggests that the Loteae and Coronilleae share a more recent ancestry with tropical tribes such as Phaseoleae and Millettieae than with other temperate tribes.     

THE MORPHOLOGY AND RELATIONSHIPS OF DALECHAMPIA SCANDENS (EUPHORBIACEAE)

The circumtropical but preponderantly American genus Dalechampia, comprising nearly 100 species of twining vines (or rarely subshrubs), is strikingly isolated within the Euphorbiaceae because of its distinctive bibracteate inflorescences. There has been considerable taxonomic controversy with regard to the relationships of the genus, and it has been suggested that Dalechampia is allied to the tribe Euphorbieae because of a supposed analogy between its inflorescence and the cyathium in the Euphorbieae. Field and laboratory investigations of the common American species D. scandens, together with a comparative survey of related species, have thrown some light on these problems. The Dalechampia inflorescence seems best interpreted as consisting of a terminal staminate pleiochasium (with part of the lateral branches transformed for nectar production), juxtaposed to a 3-flowered pistillate cyme. The lips of the conspicuous bilabiate involucre are formed by the hypertrophied bracts which subtend the staminate and pistillate cymes. The bisexual inflorescences appear to be distinctly proterogynous, rather than proterandrous, as has been previously suggested. The configuration of the inflorescence—a bilaterally symmetrical pseudanthium—suggests adaptation for crosspollination, but the closing movement of the bracts makes self-pollination probable in the absence of visits by pollinators. The similarity of the Dalechampia inflorescence to the cyathium of the Euphorbieae appears to be entirely superficial, and both reproductive and vegetative data suggest that Dalechampia is related to taxa of tribe Plukenetieae.     

THE PLATYCARYA PERPLEX AND THE EVOLUTION OF THE JUGLANDACEAE

We report on the leaves, fruits, inflorescences, and pollen of two fossil species in the genus Platycarya. The association of these dispersed organs has been established by their repeated co-occurrence at a large number of localities, and for two of the organs (fruit and pistillate inflorescence, and pollen and staminate inflorescence) by apparent organic attachment of compression fossils. Each of the two species can be distinguished by characteristics of all the known megafossil organs. We also review the fossil record of dispersed platycaryoid fruits and inflorescences, recognizing three additional species of Platycarya and two of Hooleya. Two of the fossil Platycarya species are morphologically very different from the living Platycarya strobilacea Sieb. et Zucc., but they show the diagnostic features of the genus. Hooleya is a generalized member of the Platycaryeae that is probably close to the ancestry of Platycarya. The two Platycarya species known from multiple organs provide a remarkable example of mosaic evolution in which fertile and foliar structures have attained different levels of morphological specialization. The leaves, often considered the most plastic of plant organs, retain several features that are otherwise seen only in the Engelhardieae. These similarities in leaf architecture between the fossil Platycarya species and Engelhardieae are advanced features for the Juglandaceae, and thus indicate a sister-group relationship between the two lines. In contrast to the leaves, the fruits, inflorescences, and pollen of the fossil Platycarya species are almost as specialized as those of the extant P. strobilacea and bear little resemblance to the same structures in other genera of the family. The morphology, taphonomy, sedimentary setting, and geographic and stratigraphic distribution of three of the fossil platycaryoid species suggest that they were wind-dispersed, early successional plants that grew in thickets. This habit is retained by Platycarya strobilacea and is typical of many of the amentiferae (e.g. Myricaceae, Betulaceae). The r-selected life-history pattern of the Platycarya line may well have contributed to its low diversity through geologic time.     

763. GUNDELIA TOURNEFORTII

Gundelia tournefortii L. (Compositae: Gundelieae) is described and illustrated, and its strange inflorescence morphology highlighted. The history of the discovery of this fascinating plant is covered from one of the first natural history collections made in the late 16th century in the Levant. The problematic taxonomy of this genus is discussed, both supragenerically and infragenerically. The species has very rarely been cultivated throughout its recent history, making a commentary on its cultivation and propagation a little difficult. The wide range of uses cover a history dating back at least 10,000 years, from the Neolithic sites of Iraq and Turkey, to its present day usage in the region. The importance of herbarium specimen data, as well as literature, for the ethnobotany of taxa is emphasized. A possible biblical connection is commented on in relation to the Shroud of Turin.     

THE ONTOGENY OF THE INFLORESCENCE AND FLOWER OF LIQUIDAMBAR STYRACIFLUA L. (HAMAMELIDACEAE)

A developmental study of the inflorescence of Liquidambar styraciflua L. was conducted to clarify morphological discrepancies reported in the literature. Salient features of development are: 1) the inflorescence apex results from the conversion of a terminal, vegetative apex; 2) partial inflorescence apices arise as ellipsoid structures in axils of leaves, bracts, or transitional phyllomes; 3) development of male heads is acropetal whereas female heads differentiate basipetally; 4) the partial inflorescence apex becomes segmented into several distinct subunits indicating an axillary branch system of the third order; 5) distinct individual floral primordia are initiated on the subunits; 6) a complete absence of perianth development; 7) inception of carpel primordia in flowers of lower male heads as well as female heads, but a failure of the gynoecium to develop beyond an incipient stage in male heads; and 8) development of sterile structures around the base of the styles of only female flowers near the time of anthesis. Carpellary characteristics of the sterile structures are described, their morphological nature is discussed, and the phylogenetic position of Liquidambar is evaluated.     

NEW INTERPRETATION OF THE INFLORESCENCE OF FAGUS DRAWN FROM THE DEVELOPMENTAL STUDY OF FAGUS CRENATA,WITH DESCRIPTION OF AN EXTREMELY MONSTROUS CUPULE

The inflorescence of Fagus is generally considered to be a determinate one, i.e., an axillary dichasium, in contrast to those of most genera in the family, which are indeterminate, dichasial, or simple catkins. To understand the relationship between the two types, ontogenetic development of the inflorescence of Fagus crenata was investigated. The early developmental stages are similar in both the male and the female inflorescences. At first, the inflorescence is oval-shaped, then a swelling forms at the distal side of it. Subsequently, another swelling forms at the proximal side. The more or less conspicuous residual part of the primary inflorescence axis remains between the two swellings. The inflorescence becomes heart-shaped and the first flower forms at the summit of each swelling. Subsequently, higher-ordered flowers form dichasially in the male inflorescence, and the cupule valves differentiate in the female one. This organogenetic manner suggests that the inflorescence of Fagus is an indeterminate one, consisting of two dichasia arranged alternately on the primary axis. The scale leaves surrounding the inflorescence were also given a new interpretation. They were considered to be stipules of the bracts, because sometimes they constitute a continuous structure, together with an inconspicuous swelling between them. A proliferous-type monstrous cupule was interpreted as supporting evidence for the hypothesis.     

SPIRAL DEVELOPMENTAL PATTERNS IN THE STEM AND INFLORESCENCE OF LILIUM TIGRINUM

Extensive correlations in spirality were observed among vegetative and floral organs in Lilium tigrinum Ker. Organs involved were vegetative leaves, bracts, and bracteoles. These correlations varied in their degree of constancy depending upon the organs involved. The mature inflorescences of L. tigrinum appeared to fit the common definition of a raceme. In 67.3% of the flowers at node 3 on the raceme, the bract-bracteole spirals reversed the spiral of vegetative leaves on the stem. These reversals resembled those observed on essentially cymose inflorescences of certain members of the Caryophyllaceae. Cymose branching was found to be an invariable feature of the inflorescence of L. tigrinum when secondary flowers appear. The apparently indeterminate tips of inflorescence main axes were interpreted as exhibiting stages in progression from a basically determinate (cymose) inflorescence. It was concluded that the ancestors of L. tigrinum had well-developed cymose branching patterns in the inflorescence. Reversal of stem spirals by the bract-bracteole spirals at the apices of many inflorescences was considered to be the result of complete utilization of the inflorescence meristem. Explanations for those reversals were provided by the field theory and by the theory of the first available space.     

中国盘霜霉属在菊科植物上的分类单元

本文讨论了菊科植物上盘霜霉属Bremia的分类问题。根据专性寄生菌种的划分,在以形态特征为基础的同时,结合考虑寄生专化性或寄主范围的观点,我们提出菊科植物上Bremia的种的寄主限制在菊科“族”的范围内。对中国的菊科植物上Bremia属的已知种及变种列出了检索表,还报告了一个新种及一新组合,它们是兔苣盘霜霉(B.lagoseridis sp.nov.),寄生于兔苣(Lagoseris sanctae),和蓟盘霜霉(B.cirsii comb.nov.),寄生于蓟属(Cirsium spp.),标本保存于四川农业大学真菌实验室及中国科学院微生物所标本室。     

中国菊科一新种——香紫菀北大核心CSCD

该文描述了在中国福建北部山区茫荡山发现的菊科(Compositae)紫菀属(Aster L.)一新种——香紫菀(A.artemisiaodorum X.X.Su,S.P.Chen&L.Ma sp.nov.)。基于2个核基因(ITS、ETS)和1个叶绿体基因(trn L-F)片段构建的系统发育树显示,香紫菀具有独立性,与白舌紫菀[A.baccharoides(Benth.)Steetz]互为姐妹类群,但该种形态与白舌紫菀相差较大,其全部叶两面无毛、总苞筒状、头状花序1.0~1.8 cm、舌状花5~8朵以及全株具芳香气味等特征。形态特征分析与系统发育分析均支持该新种成立。模式标本现存于福建农林大学标本馆。     

ONTOGENY OF THE INFLORESCENCE OF SAURURUS CERNUUS (SAURURACEAE)

The spicate inflorescence of Saururus cernuus L. (Saururaceae) results from the activity of an inflorescence apical meristem which produces 200–300 primordia in acropetal succession. The inflorescence apex arises by conversion of the terminal vegetative apex. During transition the apical meristem increases greatly in height and width and changes its cellular configuration from one of tunica-corpus to one of mantle (with two tunica layers) and core. Primordia are initiated by periclinal divisions in the subsurface layer. These are “common” primordia, each of which subsequently divides to produce a floral apex above and a bract primordium below. The bract later elongates so that the flower appears borne on the bract. All common primordia are formed by the time the inflorescence is about 4.4 mm long; the apical meristem ceases activity at this stage. As cessation approaches, cell divisions become rare in the apical meristem, and height and width of the meristem above the primordia diminish, as primordia continue to be initiated on the flanks. Cell differentiation proceeds acropetally into the apical meristem and reaches the summital tunica layers last of all. Solitary bracts are initiated just before apical cessation, but no imperfect or ebracteate flowers are produced in Saururus. The final event of meristem activity is hair formation by individual cells of the tunica at the summit, a feature not previously reported for apical meristems.     

COLONIZATION OF THE EPINEUSTON BY CYSTODINIUM BATAVIENSE(DINOPHYCEAE): BEHAVIOR OF THE ZOOSPORE1

Cystodinium bataviense Klebs is the first dinoflagellate observed to exhibit specialized zoospore behavior which results in colonization of the epineuston. The zoospore: (1) is strongly phototactic; (2) changes shape rapidly upon release; (3) possesses at least two types of swimming behavior, including a “stop mechanism”; and, (4) sheds its theca as the new cell wall asymmetrically elongates into the immobile vegetative stage. These features working in concert facilitate the entrance of Cystodinium into the epineuston. Detailed observations of zoospore morphology and analysis of its behavior are used as new characters to further delimit C. bataviense. Since vegetative morphology has proven unsatisfactory in circumscribing other Cystodinium species, the study of variation in zoospore characters will help to clarify taxonomic units within the genus.     

BEETLE POLLINATION OF CYCLANTHUS BIPARTITUS (CYCLANTHACEAE)

The morphology, inflorescence phenology, and insect visitors of Cyclanthus were observed during two reproductive seasons at Finca La Selva in the Atlantic lowlands of Costa Rica. The inflorescence of Cyclanthus is an elongate spadix that is subtended and enclosed by four large, cymbiform bracts. Staminate and pistillate flowers are arranged in separate cycles along the length of the spadix and show marked dichogamy. Pollinators of Cyclanthus are beetles of the genus Cyclocephala (Scarabaeidae). The beetles arrive at the inflorescence while it is in the pistillate phase, during the first evening of the 2-day flowering period. They remain in the inflorescence for 24 hrs, until the end of staminate anthesis. The bracts of the inflorescence produce specialized tissue that the beetles consume along with pollen. Chemical analysis of the food tissue indicates that it is almost 50% lipid by dry weight. The scarabs use the inflorescence as an aggregation site for mating. Experiments with bagged inflorescences showed that no seeds are produced in the absence of pollinators, which suggests that Cyclanthus is obligately allogamous.     

Inflorescence spiders: A cost/benefit analysis for the host plant,Haplopappus venetus Blake (Asteraceae)

Summary Predators on flower visitors, such as spiders, could influence plant reproduction by determining the balance between pollination and seed predation by insects. This study examines the net effect of predation by the inflorescence spider, Peucetia viridans (Hentz), for seed production by a native plant species on which it hunts. Both pollination and seed set of Haplopappus venetus (Asteraceae) were reduced on branches with spiders; however, the release of viable, undamaged seed was higher on inflorescence branches with spiders than on those without. Occurrence of P. viridans was associated with the flat-topped inflorescence branch structure characteristic of H. venetus rather than with the vertical structure of its congener, H. squarrosus. Thus, the interaction should be a reinforcing selective pressure on inflorescence branch morphology of H. venetus over time. Two factors providing constraints on the degree and rate of coevolution of the plant-spider interaction are suggested by the results: (1) the critical role of phenological synchrony and (2) the opposing requirements of interacting species and of subsequent life history stages within a species.     

A SKULL OF THE GIANT BONY‐TOOTHED BIRD DASORNIS (AVES: PELAGORNITHIDAE) FROM THE LOWER EOCENE OF THE ISLE OF SHEPPEY

Abstract: The first substantial skull of a very large Paleogene bony‐toothed bird (Pelagornithidae) is described from the Lower Eocene London Clay of the Isle of Sheppey in England. The specimen is assigned to Dasornis emuinus (Bowerbank), based on a taxonomic revision of the large London Clay Pelagornithidae. Very large bony‐toothed birds from the London Clay were known previously from fragmentary remains of non‐comparable skeletal elements only, and Dasornis londinensis Owen, Argillornis emuinus (Bowerbank), A. longipennis Owen, and Neptuniavis miranda Harrison and Walker are considered junior synonyms of D. emuinus. The new specimen allows a definitive assignment of Dasornis to the Pelagornithidae and documents that this taxon closely resembles other bony‐toothed birds in cranial morphology. It is hypothesized that giant size (i.e. a wingspan above 4 m) evolved only once within Pelagornithidae and that Dasornis emuinus is the sister taxon of the giant Neogene bony‐toothed birds, which share a derived wing morphology.     

Cloning of cDNA coding for dihydroflavonol-4-reductase (DFR) and characterization of dfr expression in the corollas of Gerbera hybrida var. Regina (Compositae)

We are approaching corolla differentiation in Compositae by studying the regulation of flavonoid pathway genes during inflorescence development in gerbera. We have cloned a dfr cDNA from a ray floret corolla cDNA library of Gerbera hybrida var. Regina by a PCR technique based on homologies found in genes isolated from other plant species. The functionality of the clone was tested in vivo by complementing the dihydrokaempferol accumulating petunia mutant line RL01. By Southern blot analysis, G. hybrida var. Regina was shown to harbour a small family of dfr genes, one member of which was deduced to be mainly responsible for the DFR activity in corolla. Dfr expression in corolla correlates with the anthocyanin accumulation pattern: it is basipetally induced, epidermally specific and restricted to the ligular part of corolla. By comparing the dfr expression in different floret types during inflorescence development, we could see that dfr expression reflects developmental schemes of the outermost ray and trans florets, contrasted with that of the disc florets.