THE ULTRASTRUCTURE OF ACACIA CORNIGERA L. BELTIAN BODY TISSUE

Beltian bodies of Acacia cornigera have evolved as multicellular structures which serve as food for protective ant colonies. At the ultrastructural level, Beltian body cells contain a large amount of protein and lipid that presumably contribute to the ant's nutrition. The non-soluble protein is aggregated into tubules of two size classes: one is present in both the cytoplasm and nucleoplasm, and has an individual tubule diam of 75 A, while another size class, located in the cytoplasm, has a diam of 280 A. These two classes of protein tubules aggregate into units that occupy a high percentage of a cortical cell's volume. Numerous lipid droplets are present in the cytoplasm, adding an energy source to the ant's diet. Each droplet is surrounded by a single layer of filaments, the molecular composition of which is unknown at this time. This study indicates that the evolutionary development of this tissue has produced a highly desirable food source for the inhabiting ants.     

EARLY HISTOGENESIS OF THE ADULT LEAVES OF DARLINGTONIA CALIFORNICA (SARRACENIACEAE) AND ITS BEARING ON THE NATURE OF EPIASCIDIATE FOLIAR APPENDAGES

In order to assess the validity of various interpretations of tubular leaves of angiosperms, a histogenetic study of the ontogeny of adult leaves of Darlingtonia californica was undertaken. The adult leaf of Darlingtonia is characterized by a sheathing leaf base, an elongate ascidium, an overarching hood, and two “fishtail” appendages which arise near the leaf apex. A keellike growth, with two rows of alternate vascular bundles, traverses the tube from base to mouth. Ontogenetic studies show that the primordium arises by a monopodial rather than a sympodial mode of growth as previously reported. After the formation of a small, erect primordium, a restricted adaxial meristem is initiated that expands both adaxially and upwards. This “querzone” serves, in effect, to congenitally combine the two primordial margins during its extension. Growth and maturation of the subjacent portions cause tubular elongation in the leaf. Primordial apical divisions are later replaced by more general intercalary growth with acropetal and centrifugal maturation. The hood and fishtails are established early in ontogeny by adaxial growth of the primordial apex and subsequent activation of juxtaposed localized meristems. Comparative morphology has established that the epiascidiate leaf is a foliar appendage that undergoes certain specific morphogenetic modifications. It has a structural relationship to ensiform appendages of Acacia and Acorus as well as to peltate foliar organs. The early ontogeny of Darlingtonia leaves is considered to be homologous with other epiascidiate foliar organs, including some supposedly primitive carpels.     

ROLE OF STEM GROWTH IN LINUM USITATISSIMUM LEAF TRACE PATTERNS

Linum usitatissimum stem growth parameters were quantified by computer-assisted analyses of scanning electron micrographs of shoot apical meristems throughout ontogeny. There were progressive decreases in the plastochron and relative plastochron rates of radial and vertical stem growth which resulted in the generation of progressively higher orders of contact parastichy phyllotaxis throughout ontogeny. The change in the relative spacing of primordia initiation on the stem coupled with the iterative differentiation of leaf gap and interfascicular ray parenchyma associated with each leaf primordium resulted in the delimitation of progressively higher orders of leaf trace interconnections throughout ontogeny. A set of developmental rules was generated which should permit simulation of many leaf trace patterns.     

Spiderling sex ratio and maternal investment in the bolas spider Mastophora cornigera (Araneae,Araneidae)

Male Mastophora cornigera exit egg sacs as adults, which allowed us to determine spiderling sex ratios and patterns of maternal investment in this species. We collected 15 egg sacs produced by seven mothers, which yielded 1945 emergent spiderlings which were sexed, 1850 of which were weighed. Two emergent broods were significantly male and female biased and were unaffected by pre-emergence mortality. The weights of male and female spiderlings differed in eight broods, with males and females being heavier in four cases each. Five of these broods were derived from multiple egg sac sets produced by one mother, and in each case, the total mean male and female spiderling weights for all broods in a set were biased in the same direction as the biased brood(s) within that set. Mean emergent spiderling weight was independent of brood size and sex ratio for both males and females. Despite such independence, sex allocation in M. cornigera can favor sons, daughters, or both equally, and by numbers, by weight, or both at once. The proximate mechanisms and adaptive significance of such variability is unknown. We also review evidence for gender-biased allocations in arachnid offspring and suggested mechanisms for their applicability to M. cornigera.     

THE ORGANIZATION OF THE VASCULAR SYSTEM IN THE STEMS OF THE NYMPHAEACEAE. I. NYMPHAEA SUBGENERA CASTALIA AND HYDROCALLIS

The vascular system in the stems of Nymphaea odorata and N. mexicana subgenus Castalia, and N. blanda subgenus Hydrocallis consists of continuing axial stem bundles with eight being the usual number. The stem bundles are concentric and xylem maturation is mesarch. Xylem elements consist of tracheids with spirally or weakly reticulated secondary wall thickenings. The phloem is made up of companion cells and short sieve tube members with simple sieve plates that are nearly transverse. At the node each leaf is supplied with two lateral leaf traces and a median leaf trace. A root trace is also present and supplies a series of adventitious roots borne on the leaf base. Flowers and vegetative buds develop directly from the apical meristem and occupy leaf sites in a single genetic spiral. Each flower or vegetative bud is related to a leaf through specific spatial and vascular association. The related leaf is separated from the related flower by three members of the genetic spiral and occupies an adjacent orthostichy. Vascular tissue for the related flower arises from the inner surfaces of the four stem bundles supplying leaf traces to the related leaf and extends through the pith to the flower or vegetative bud via a peduncle fusion bundle. The vascular system organization in the investigated species of Castalia and Hydrocallis is not typically monocotyledonous or dicotyledonous, nor can it be considered transitional between them. The ontogeny of the vascular system is similar to typical dicotyledons and the investigated species of Nymphaea can, therefore, be considered to represent highly specialized and modified dicotyledons.     

ROLE OF PARENCHYMA IN LINUM USITATISSIMUM LEAF TRACE PATTERNS

A new notation for leaf trace patterns was developed which is consistent with contemporary contact parastichy phyllotaxis notation. New computer-aided methods for generating accurate stem tissue maps were developed. Application of these methods resulted in clarification of the role that parenchyma differentiation plays in delimiting the procambial template for Linum usitatissimum L. stem vasculature through ontogeny. Study of the tissue maps for the various leaf trace patterns exhibited by Linum stems through ontogeny generated a set of observations which permits more rigorous definition of the developmental rules for vascular pattern formation. Long-known geometric principles of phyllotaxis were found applicable to leaf trace patterns.     

The exploitation of an ant-defended host plant by a shelter-building herbivore

Larvae of a Polyhymno species (Lepidoptera: Gelechiidae) feed on the ant-defended acacia, Acacia cornigera, in the tropical lowlands of Veracruz, Mexico. Polyhymno larvae construct sealed shelters by silking together the pinna or pinnules of acacia leaves. Although larval density and larval survival are higher on acacias not occupied by ants, shelters serve as a partial refuge from the ant Pseudomyrmex ferruginea (Hymenoptera: Formicidae), which defends A. cornigera plants; thus, shelters provide Polyhymno larvae access to an ant-defended host plant. P. ferruginea ants act as the primary antiherbivore defense of A. cornigera plants, which lack the chemical and mechanical defenses of non-ant-defended acacias. Thus, defeating the ant defense of A. cornigera provides Polyhymno larvae access to an otherwise poorly defended host plant. Damage caused by Polyhymno larval feeding reaches levels which can kill A. cornigera plants. Received: 6 June 1996 / Accepted: 6 September 1996     

Herbivory in a spider through exploitation of an ant–plant mutualism

Spiders are thought to be strict predators [1]. We describe a novel exception: Bagheera kiplingi, a Neotropical jumping spider (Salticidae) that exploits a well-studied ant–plant mutualism, is predominantly herbivorous. From behavioral field observations and stable-isotope analyses, we show that the main diet of this host-specific spider comprises specialized leaf tips (Beltian food bodies; Figure 1A) from Vachellia spp. ant-acacias (formerly Acacia spp.), structures traded for protection in the plant's coevolved mutualism with Pseudomyrmex spp. ants that inhabit its hollow thorns [2]. This is the first report of a spider that feeds primarily and deliberately on plants.     

THE CUTICULAR ANATOMY OF FRENELOPSIS VARIANS FROM THE LOWER CRETACEOUS OF CENTRAL TEXAS

Stem fragments identified as Frenelopsis varions Fontaine have been found in the Lower Cretaceous (Albian) of central Texas. The cuticle is extremely thick and characterized by 5–6 subsidiary cells with papillae overarching the stomatal chamber. Guard cells are deeply sunken below the epidermis. Stomatal complexes are arranged in axial rows extending from the base of an internode to its apex. The rows of stomata continue into the sheathing leaf where the rows curve towards the leaf apex. The epidermis of F. varions was apparently long persistent and underwent prolonged growth. Axial rows of stomata are frequently disrupted resulting in a random pattern of stomata. A single, highly reduced, sheathing leaf is present at each node. The margin of the leaf has numerous unicellular trichomes and extends to form a slightly triangular blade.     

EXPRESSION OF PNA,WGA, SBA,AND Con A LECTIN RECEPTORS IN THE ADULT AND DEVELOPING HONEYBEE ANTENNAL LOBE

Glycoproteins are thought to play a crucial role in cell—cell interactions during nervous system ontogeny both in vertebrates and invertebrates. In order to investigate the putative involvement of such molecules during bee brain ontogeny we used lectins for their ability to bind specifically carbohydrate moieties. The expression of four lectin receptors, i.e. Arachis hypogea (PNA), Triticum vulgaris (WGA), Glycine max(SBA), and Concanavalin A (Con A) has been studied during pupal development and in the adult. The antennal lobe shows a complementary pattern of expression of Con A which stains both neuron somata and glomerular contours, and PNA, which stains the glomerular neuropile. SBA strongly stained the perineurium, trachea and mushroom body neuropile, while other neuropiles were not stained. WGA stained neuronal somata and the core of the glomeruli.     

Petrocodon multiflorus sp. nov. (Gesneriaceae) from Guangxi,China

Petrocodon multiflorus F. Wen & Y. S. Jiang sp. nov. (Gesneriaceae) is described and illustrated. It is most similar to P. dealbatus Hance, but can be distinguished by its leaf lamina texture, shape of leaf margins, and by the number of cymes borne by an individual plant and the number of flowers in each cyme. A key to the species of Petrocodon is provided.     

Are ontogenetic shifts in foliar structure and resource acquisition spatially conditioned in tank‐bromeliads?

The phenotypic plasticity of plants has been explored as a function of either ontogeny (apparent plasticity) or environment (adaptive plasticity), although few studies have analyzed these factors together. In the present study, we take advantage of the dispersal of Aechmea mertensii bromeliads by Camponotus femoratus or Pachycondyla goeldii ants in shaded and sunny environments, respectively, to quantify ontogenetic changes in morphological, foliar, and functional traits, and to analyze ontogenetic and ant species effects on 14 traits. Most of the morphological (plant height, number of leaves), foliar (leaf thickness, leaf mass area, total water content, trichome density), and functional (leaf δ¹³C) traits differed as a function of ontogeny. Conversely, only leaf δ¹⁵N showed an adaptive phenotypic plasticity. On the other hand, plant width, tank width, longest leaf length, stomatal density, and leaf C concentration showed an adaptation to local environment with ontogeny. The exception was leaf N concentration, which showed no trend at all. Aechmea mertensii did not show an abrupt morphological modification such as in heteroblastic bromeliads, although it was characterized by strong, size‐related functional modifications for CO₂ acquisition. The adaptive phenotypic variation found between the two ant species indicates the spatially conditioned plasticity of A. mertensii in the context of insect‐assisted dispersal. However, ant‐mediated effects on phenotypic plasticity in A. mertensii are not obvious because ant species and light environment are confounding variables. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 175 , 299–312.     

TRICHOMES AND CANNABINOID CONTENT OF DEVELOPING LEAVES AND BRACTS OF CANNABIS SATIVA L. (CANNABACEAE)

Trichome density and type and cannabinoid content of leaves and bracts were quantitated during organ ontogeny for three clones of Cannabis sativa L. Trichome initiation and development were found to occur throughout leaf and bract ontogeny. On leaves, bulbous glands were more abundant than capitate-sessile glands for all clones, although differences in density for each gland type were evident between clones. On pistillate bracts, capitate-sessile glands were more abundant than the bulbous form on all clones, and both types decreased in relative density during bract ontogeny for each clone. The capitate-stalked gland, present on bracts but absent from vegetative leaves, increased in density during bract ontogeny. The capitate-stalked gland appeared to be initiated later than bulbous or capitate-sessile glands during bract development and on one clone it was first found midway in bract ontogeny. Nonglandular trichomes decreased in density during organ ontogeny, but the densities differed between leaves and bracts and also between clones. Specific regulatory mechanisms appear to exist to control the development of each trichome type independently. In addition, control of trichome density seems to be related to the plant organ and clone on which the gland type is located. Cannabinoid synthesis occurs throughout organ development and is selectively regulated in each organ. Typically, cannabinoid synthesis occurred at an increasing rate during bract development, whereas in developing leaves synthesis occurred at a decreasing rate. Cannabinoid content on a dry weight basis was generally greater for bracts than leaves. Analyses of leaves indicate that other tissues in addition to glands may contain cannabinoids, while for bracts the gland population can accommodate the cannabinoid content for this organ. The functional significance of trichomes and cannabinoids in relation to evolution is discussed.     

The relationship between ontogeny, morphology, and diet in the Chinese hook snout carp (Opsariichthys bidens)

The relationship of changes of body and mouth shape with diet during ontogeny in the Chinese hook snout carp Opsariichthys bidens was examined. Shape changes were analyzed using geometric morphometrics. Body shape changed from a shallow body to a deep body as size increased. Similarly, the head of O. bidens changed from an upward-pointing direction to a downward-pointing directing as size increased. The position of the eye also changed during ontogeny, with large individuals having an eye situated higher on the head than small individuals. The conspicuous symphyseal knob on the lower jaw of O. bidens results in a typical zigzag pattern of the jaw. The zigzag pattern became more pronounced as fish grew larger. No difference in body shape or jaw shape was found between males and females. The shape changes were associated with changes in diet, suggesting that diet choice over the course of ontogeny has a strong impact on body shape. Benthic macroinvertebrates and zooplankton dominated the diet of small individuals, medium-size individuals specialized in benthic macroinvertebrates, and fish dominated the diet of large individuals.     

The Specific Density of a Leaf as a Characteristic of the Photosynthetic Apparatus

At early stages of ontogeny (up to 50–60% of the maximum leaf area) of wheat (Triticum aestivumL.), meadow fescue (Festuca pratensisHuds.), reed fescue (F. arindinaceaSchreb.), and sugar beet (Beta vulgarisL. var. saccharifera(Alef) Krass), there is a correlation between changes in the specific leaf density (SLD); photosynthetic CO₂assimilation rate; activity of the key photosynthetic enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39); and the concentrations of chlorophyll (Chl) a, Chl b, carotenoids, and soluble leaf proteins. However, the SLD does not correlate with the activity of phospho(enol)pyruvate carboxylase (EC 4.1.1.31). Senescence was accompanied by a decrease in the leaf SLD. Treatment with cytokininomimetics (6-benzylaminopurine and Metribuzin) caused an increase in the SLD. The specific leaf density is suggested to be a structural and functional characteristic of the photosynthetic apparatus of agricultural plants.     

THE ROLES OF HETEROCHRONY AND HETEROBLASTY IN THE DIVERSIFICATION OF LEAF SHAPES IN BEGONIA DREGEI (BEGONIACEAE)

The relationship between shape variation in the transitional series of leaves and in adult leaves was examined in seedlings of seven morphs of Begonia dregei using several quantitative methods of shape analysis. There is variation in the shape of adult leaves among individuals as well as in juvenile leaves within individuals in B. dregei. As an individual grows, there is a gradual transition in leaf shape from the symmetrical, oval, smooth-margined leaves through a series of more than ten transitional leaves to a stable adult leaf shape. There appear to be two basic patterns to the acquisition of adult traits. Traits that differ among morphs are acquired gradually throughout the entire transitional series while those that are similar among morphs are acquired by about leaf 5 and remain stable through the later juvenile leaves. There is no identity of leaf shape between the earlier leaves of some morphs and the later leaves of others. Evolutionary diversification in adult leaf morphology in this species is not related to simple changes in ontogeny of the whole plant.     

COMPARISON OF EARLY LATERAL VEIN FORMATION IN LINUM USITATISSIMUM LEAVES WITH THEORETICAL NETWORK MODELS

The plastochron age of the Linum leaf that first exhibited lateral leaf vein divergences, the divergent leaf, increased through shoot ontogeny, but the size of the divergent leaf remained constant. There were progressive decreases in the plastochron and relative plastochron rate of leaf elongation, but no significant change in relative chronological rate of leaf elongation, through ontogeny. Thus, divergent leaves of similar sizes occupied different relative positions in the array of leaves on stems of different plastochron ages. These observations are partially consistent with theoretical network model predictions on early leaf vein development. The empirical data of this study suggest additional features of leaf development that should be incorporated into future simulation models for leaf vein development.     

Potential aposematism in an insular tree species: are signals dishonest early in ontogeny?

Recent investigations have suggested that some plants are aposematic. Our understanding of how aposematism varies through plant ontogeny, however, is incomplete. Furthermore, the potential for lower leaf surfaces to signal to vertebrate herbivores that are viewing leaves from below has not been investigated. Here, we investigate ontogenetic changes in leaf colour in Pseudopanax crassifolius (Araliaceae), a tree species that is endemic to New Zealand. We demonstrate that P. crassifolius produces lateral leaf spines that peak in size during the sapling stage of development. Spots of brightly coloured tissues on the upper leaf surfaces may be warning signals. The intensity of these signals, however, peaked at the seedling stage, providing a dishonest signal of defence. Conversely, signals on lower leaf surfaces peaked in the sapling stage, providing an honest defensive signal later in ontogeny. Lateral leaf spines and all potential warning colours were absent in adults, after they grow above the reach of the largest known native megaherbivores (moa – Aves: Dinornithiformes). Overall, these results suggest that aposematism may vary predictably through plant ontogeny in response to the changing perspective of herbivores as plants grow vertically.     

Species in the genus Rhytidelasma Gaud (Acarina: Pterolichidae) from the Green Conure,Aratinga holochlora (Sclater) (Aves: Psittacidae)

Three species in the genus Rhytidelasma Gaud (Pterolichoidea: Pterolichidae) are known from the Green Conure, Aratinga holochlora (Sclater): R. cornigera n. sp., R. urophila n. sp. and R. mesomexicana Atyeo et al. The new species are described, and the microhabitat(s) for each species discussed.