Horizontal orientation of zygomorphic flowers: significance for rain protection and pollen transfer.

Floral traits are recognized to have evolved under selection for abiotic and biotic factors. Complex zygomorphic flowers usually face horizontally. It has been proved that a horizontal orientation facilitates pollinator recognition and pollination efficiency, but its significance in adaptation to abiotic factors remains unknown. The floral orientation of Abelia × grandiflora naturally varies around horizontal (with an angle of -30 to +33° between the floral main axis and the horizontal). We examined whether three different floral orientations affected flower thermal conditions, response to rain and pollination. Results showed that floral orientation had no effect on diurnal variations in flower temperature. The anthers of all three flower orientations were wetted by rainfall, but the inclined upward-facing flowers contained significantly more rainwater. The horizontal flowers received significantly higher visitation by hawkmoths and had a higher stigmatic pollen load. In contrast, the upward flower orientation reduced pollination precision, while downward-facing flowers had decreased pollinator attraction. This study indicates that horizontal flowers may have evolved as a trade-off between rain protection and pollination. Zygomorphic flowers that deviate from a horizontal orientation may have lower fitness because of flower flooding by rainwater and decreased pollen transfer.

Diversification of CYCLOIDEA expression in the evolution of bilateral flower symmetry in Caprifoliaceae and Lonicera (Dipsacales).

BACKGROUND AND AIMS: The expression of floral symmetry genes is examined in the CYCLOIDEA lineage following duplication, and these are linked to changes in flower morphology. The study focuses on Dipsacales, comparing DipsCYC2 gene expression in Viburnum (radially symmetrical Adoxaceae) to members of early-diverging lineages of the bilaterally symmetrical Caprifoliaceae (Diervilla and Lonicera). METHODS: Floral tissue from six species, which included dorsal, lateral and ventral regions of the corolla, was dissected. RNA was extracted from these tissues and each copy of DipsCYC2 was amplified with reverse transcriptase PCR. KEY RESULTS: Members of DipsCYC2 were expressed across the corolla in the radially symmetrical Viburnum plicatum. A shift to bilaterally symmetrical flowers at the base of the Caprifoliaceae was accompanied by a duplication of the DipsCYC2 gene, resulting in DipsCYC2A and DipsCYC2B, and by loss of expression of both of these copies in the ventral petal. In Lonicera (Caprifolieae), there is a shift from flowers with two dorsally and three ventrally oriented corolla lobes to a clear differentiation of dorsal, lateral and ventral lobes. This shift entailed a decoupling of expression of DipsCYC2A and DipsCYC2B; DipsCYC2B continues to be expressed in the dorsal and lateral lobes, while DipsCYC2A expression is restricted to just the two dorsal lobes. A reversion to more radially symmetrical flowers within Lonicera was accompanied by a re-expansion of expression of both DipsCYC2A and DipsCYC2B. CONCLUSIONS: The transition to bilateral symmetry in Caprifoliaceae involved: (a) duplication of an ancestral DipsCYC2 gene; (b) the loss of expression of both of these copies in the ventral petal; and (c) changes in the zone of expression, with one copy continuing to be expressed across the dorsal and lateral petals, and the other copy becoming restricted in expression to the dorsal corolla lobes.

Evolution of fruit and seed characters in the Diervilla and Lonicera clades (Caprifoliaceae, Dipsacales).

BACKGROUND AND AIMS: The Diervilla and Lonicera clades are members of the family Caprifoliaceae (Dipsacales sensu Donoghue et al., 2001, Harvard Papers in Botany 6: 459-479). So far, the intergeneric relationships of the Lonicera clade and the systematic position of Heptacodium remain equivocal. By studying fruit and seed morphology and anatomy, an attempt is made to clarify these issues. In addition, this study deals with the evolution of fruit and seed characters of the Diervilla and Lonicera clades with reference to allied taxa. METHODS: Light and scanning electron microscopy were used for the morphological and anatomical investigations. Phylogenetic analyses were carried out by applying the parsimony and Bayesian inference optimality criteria. Character evolution was studied by means of parsimony optimization and stochastic character mapping. KEY RESULTS: Diervilla and Weigela (Diervilla clade) are characterized by several unique traits in Dipsacales, including capsules with numerous seeds, seed coats without sclerified outer tangential exotestal cell walls, and dehiscent fruits. Seeds with completely sclerified exotestal cells and fleshy fruits characterize the Lonicera clade. Leycesteria and Lonicera have berries, ovaries without sterile carpels and several seeds per locule, whereas Symphoricarpos and Triosteum have drupes, ovaries with one or two sterile carpels and a single seed per locule. Heptacodium shares several characteristics with members of the Linnina clade, e.g. achenes, single-seeded fruits and a compressed, parenchymatous seed coat. CONCLUSIONS: The results confirm the monophyly of the Diervilla and Lonicera clades and allow us to hypothesize a close relationship between Leycesteria and Lonicera and between Symphoricarpos and Triosteum. Fruit and seed morphology and anatomy point to a sister relationship of Heptacodium with the Linnina clade, rather than with the Lonicera clade.

Caracterização farmacobotânica das espécies de Sambucus (Caprifoliaceae) utilizadas como medicinais no Brasil: Parte II. Sambucus australis Cham. & Schltdl. / Pharmacobotany of Sambucus species (Caprifoliaceae), used in traditional medicine in Brazil: Part II. Sambucus australis Cham. & Schltdl

Sambucus australis Cham. & Schltdl. (sabugueiro-do-rio-grande, Caprifoliaceae) é uma planta medicinal descrita apenas na primeira edição da Farmacopéia Brasileira. A espécie é nativa no Brasil, e suas flores são utilizadas na medicina popular, na forma de infusão ou decocção, como diuréticas, antipiréticas, antiinflamatórias, laxativo leve e no tratamento de doenças do aparelho respiratório. Visando elaborar uma monografia farmacopéica atualizada e comparativa com a de Sambucus nigra L., de origem européia, foram estabelecidos os caracteres botânicos macro e microscópicos, através da metodologia clássica utilizada em morfoanatomia vegetal. São características macroscópicas: flores morfologicamente monoclinas; corola de sete a dez milímetros de diâmetro; pétalas com cinco, raro quatro nervuras paralelas; estames curtos e longos; gineceu em regra com cinco lóculos. São características microscópicas: cutícula espessa e estriada; ausência de idioblastos de areia cristalina de oxalato de cálcio; estômatos anomocíticos; brácteas anfiestomáticas; sépalas hipoestomáticas; pétalas anfi-hipoestomáticas; células epidérmicas da face abaxial de sépalas e pétalas retilíneas a sinuosas; células epidérmicas do filete alongadas e de paredes retilíneas; tricomas tectores e glandulares de diferentes tipos; brácteas, sépalas e pétalas com mesofilo homogêneo; sistema vascular representado por feixes colaterais ou agrupamentos de elementos xilemáticos; presença de gotas lipídicas em todas as peças.

Sambucus australis Cham. & Schltdl. (sabugueiro-do-rio-grande, Caprifoliaceae) is a medicinal plant described only in the first edition of Brazilian Pharmacopoeia. This species is native to Brazil, and its flowers are used in the folk medicine, with diuretic purpose, antipiretic, anti-inflammatory, mild laxative and to treat respiratory diseases, on infusions or decoctions forms. Aiming at elaborating an updated pharmacopoeical monograph and comparing it with the monograph of Sambucus nigra L., from Europe, it was established the macro and microscopic botanical characters, through the classic methodology used in plant morpho-anatomy. The macroscopic characters are: morphologic monoclin flowers; corolla with seven to ten millimeters of diameter; petals with five, rarely four parallel veins; shorter and longer stamens; ovary oftenly with five locules. The main microscopic characters are: thickned and striated cuticule; absense of idioblasts with calcium oxalate sandy cristals; anomocytic stomatas; amphystomatic bracts; hypostomatic sepals; amphi-hypostomatic petals; wavy and straight epidermal cells in the lower surface of sepals and petals; filaments epidermal cells with narrow and straight walls; glandular and non-glandular trichomes of different types; homogeneous mesophyll in bracts, sepals and petals; vascular system represented by both collateral bundles and xylematic elements; volatile and non volatile oil globules in all structures.