S. Vogel’s research while affiliated with University of Vienna and other places

Traditional breeding of ornamentals has led to a scent reduction of many floricultural varieties due to a negative correlation between flower longevity and fragrance. Vigna caracalla L. Verdc. (Leguminosae: Papilionoideae) produces large flowers with an intense, pleasant fragrance. The objective of this study was to identify, using headspace analysis, the major volatiles present in the floral bouquet of cut flowers. The eluted volatiles were analyzed using a gas chromatograph linked to a mass spectrometer. The volatile profile of V. caracalla flowers consists of a complex mixture, with a total of 29 compounds being detected in quantifiable amounts. Up to now, the studied fragrance related genes come mainly from few plant species; V. caracalla could be used as floral scent research material, and in the future, the genomic approach may be applied to cloning of fragrance related genes.

The new monotypic genus Ameroglossum EB. FISCHER, S. VOGEL & A. LOPES with the new species A. pernambucense EB.FISCHER, S. VOGEL & A. LOPES from Brazil is described. It differs from the related genera in the long staminode, which is diminutive or absent in Russelia or completely absent in Eremogeton and Hemichaena. Another characteristic feature of Ameroglossum is the lower lip of corolla, which looks undivided and tongue-like, but actually is minutely 3-lobed at apex.Aus Brasilien wird die neue monotypische Gattung Ameroglossum EB. FISCHER, S. VOGEL & A. LOPES mit der neuen Art A. pernambucense EB. FISCHER, S. VOGEL & A. LOPES beschrieben. Sie unterscheidet sich von den Nachbargattungen durch ein langes Staminodium, das bei Russelia nur winzig ist oder fehlt und das den Gattungen Eremogeton und Hemichaena vollständig fehlt. Ein charakteristisches Merkmal von Ameroglossum ist die. Unterlippe der Krone, die ungeteilt und zungenartig erscheint, aber in Wirklichkeit an der Spitze undeutlich dreigeteilt ist.

Mimosa lewisii (Section Batocaulon), a shrub of the NE-Brazilian Caatinga, presents huge (pseudo-)racemes that form a separate storey overtopping the foliage. Racemes persist, developing intermittently pedunculate capitula over a period of more than one year. The brush-type, whitish flower heads are nocturnal in anthesis and active only a single night. Florets are relatively large and stout for the genus, hermaphroditic, with stiff filaments and style, and converge towards the periphery of the raceme. When expanding at dusk, the heads produce large nectar drops (up to 173 l per head), that averages 25–29% sucrose. Production starts sequentially among florets of a capitulum. The drops are freely exposed, held between the filaments. The glossophagine bat Lonchophylla mordax was observed as the only legitimate visitor; hummingbirds exploited worn capitula at daytime, but did not pollinate. The bats lapped the nectar while hovering without apparently putting out their tongues. Pollen transmission was by the snout and probably by touching neighbouring flower heads with the wings. The blossoms, of a genus predominantly entomophilous, reveal habitual adaptation to bat pollination in most of their features. Small size (14 mm in diam.) and lack of a perceptible scent suggest that an evolutionary shift towards chiropterophily is still incomplete. A brief survey of the known distribution of bat pollination in Mimosaceae is appended.

The flower of Nelumbo nucifera displays some highly specialized structural details apparently related to its pollination ecology. The functional significance of these structures, however, is still under debate. This paper presents new anatomical and chemical data that contribute to our knowledge of the floral life of the lotus. Special focus is directed on the source of scent and heat production, the role of the staminal appendages, and stigma characteristics. The receptacle, the staminal appendages and connectives are covered with a papillose, osmogenous epithelium and function as osmophores. A fractioned GC-analysis revealed that mainly 1,4-dimethoxybenzene (1,4-DMB) is emitted by these parts, whereas high amounts of C15 – C17-alkanes, n-alkenes, n-alcadienes and n-alkatrienes dominated the volatile blend that was diffusely emitted by the petals. In accordance with the literature, absolute predominance of 1,4-DMB and pentadecane was found, while some differences occurred in minor components. The active source of heat generation, apparently a means to enhance fragrance volatilization, was the receptacle. The compact mesenchyma underlying its upper platform and flanks is glandular and rests on a storage zone replete with starch that becomes exhausted during the metabolic flare-up. Spot measurements confirm the flowers capacity to maintain a temperature level of ca. 31 C by compensating the environmental temperature fluctuations. The staminal appendages warm up because they are close to the receptacle; they are not actively thermogenous, as formerly proposed. Their starch load remains nearly unaffected until defloration. The appendages, besides contributing to olfaction, may represent food bodies. Along with the pollen – shed at the male stage of anthesis – the appendages may function as a primary attractant for coleopteran pollinators, an interpretation corroborated by the remaining floral traits, which suggest the cantharophilous syndrome. Published field data, so far only available for the American subspecies, reveal variable mixed assemblages of insect visitors; no feeding on the staminal appendages is recorded. Possibly, the system once involved a partnership that has not persisted during the long history of the genus, which is nowadays attended by opportunists.

The thermo-osmotically driven air stream that temporarily ventilates the plant body of Nelumbo nucifera, supplying rhizome and roots with oxygen, takes its way through interconnected canals and caverns. The course of this circulation, starting with the uptake of gas through leaf stomata and ending with its expulsion via the specialized navel (central plate) of the leaves, as well as organs regulating the circuit, were examined using anatomical, pneumatic, and silicone casting methods. The aerenchyma of the peltate leaf, closely paralleling the nervature, is divided into four separate domains: two mirroring lateral halves including halves of the central plate, and each half again separated into an adaxial (basal) and abaxial (distal) sector. Gas absorbed by the adaxial sectors flows through a definite pair of pipes down the petiole into three lateral pairs of the eight main tubes of the horizontal shoot. There it passes several nodes with adjoining leaves, where homologous ducts, arranged in series along the shoot, contribute to the gas flux in its basipetal course. A reverse gas flow, confined to another pair of cauline pipes and also arranged in series, enters in the nodes another pair of petiolar pipes that directly lead to the foliar central plates, where it is released through stomatal pores. These pores are three times as large as the laminal stomata and control the gas release by opening and closing. Each abaxial leaf sector is, apart from its ducts leading down the petiole, via a shortcut connected with the upstream pipes supplying the central plate, so that its air circuit, when active, is only intralaminar and does not join the entirety of the system. The question where, and how, the two downstreaming currents merge into the two upstreaming ones remains unresolved. The structure of the two types of air canal diaphragms, petiolar and nodal, are documented by SEM.

Floral adaptation to pollination by bats is rare in Acanthaceae and only known from neotropical species. Two novel cases are described in detail from field observations. Harpochilus neesianus, a shrub endemic in NE Brazil, with long emergent thyrses, was seen being regularly visited by hovering glossophagine bats (Glossophaga soricina). Its large, pale lemon-green corollas are strongly bilabiate, a shape uncommon in the syndrome. The lower lip segments are recurved and the upper lip is reduced to a narrow, arcuate, tubular organ serving to support stamens and style. A sour, cabbage-like odour is released, and copious nectar is secreted by a voluminous disk. Pollen is transferred by the bat's upper, rear surface. Anthesis is confined to a single night. Chiropterophily in Ruellia eurycodon is deduced from the floral syndrome. The flowers of this shrub, studied in Goyás, Central Brazil, share the same features as Harpochilus except for the corolla shape, which conforms to the "short bell type" frequent in neotropical bat flowers. Based on literature sources, bat pollination is also predicted for Ruellia malaca and R. exostemma from Venezuela. The occurrence of this floral type in other genera of the family is briefly surveyed.

Apart from the typical, multifaceted calcium oxalate druses distributed in the mesenchyma of Nelumbo nucifera, another, unique type of druse idioblast exists in this plant. They loosely cover the lateral surface of the obconical flower receptacle. Based on light and SEM microscopy, their structure and ontogeny are described for the first time. The crystal complex consists of a flat, usually six-rayed, sharp-pointed star positioned above, and parallel to, the epidermal surface. The idioblast is supported and elevated by six adjacent columnar epidermal cells alternating with the crystal spikes. The spikes represent individual, lamellate crystals symmetrically arranged around a core of crystal sand. In the ontogeny, six steps can be discerned: 1) Enlargement and dome-like emergence of the idioblast. 2) Appearance of vacuoles below the distal endopolyploid nucleus. 3) The vacuoles coalesce and minute crystal particles collect in the vacuole and aggregate to a cluster. 4) A small six-rayed primary druse forms at a variable position. 5) The druse migrates to the cell top, becomes strictly parallel to the epidermal surface, and while the cell head further expands, a second star complex develops, becoming superimposed on the primary druse, its spikes bulging out the thin cell wall. 6) The cytoplasm vanishes and the proximal cell section becomes compressed by the surrounding columnar cells. Because the star-like bodies are confined to the nutrient-rich receptacle, are freely exposed and easily detached, they represent specialized modifications of the internal druses and apparently serve as a deterrent against herbivory.

This is the first report of corolla-borne secretory trichomes that substitute in role for a non-functional disc in a species of the neotropical genus Lundia A. DC. (Bignoniaceae). The floral biology and flowering phenology of Lundia cordata were investigated at two remnants of tropical rainforest in northeastern Brazil. This species is a typically omithophilous liana, with reddish, tubular, scentless flowers. The flowers are resupinate, protandrous and last for 2 d. There is a vestigial non-functional perigynous disc and nectar is secreted by glandular trichomes distributed along the internal surface of the corolla. The nectar is stored at the base of the corolla tube, thus showing secondary nectar presentation. The nectariferous trichomes are multi-cellular, uniseriate, with a basal foot cell rooting in the epidermis, one neck cell, and a glandular head with 13 cells on average. Three species of hummingbirds (Amazilia fimbriata, Eupetomena macroura and Phaethornis pretrei) serve as pollinators. Phaethornis ruber, Xylocopa bees, wasps and diurnal moths are considered nectar thieves.

: The pollination of Angelonia cornigera Hook. (Scrophulariaceae) was studied in Caatinga vegetation, in the municipality of Buíque, Pernambuco state, northeastern Brazil. The plant is a perennial of open areas. Up to 60 flowers are produced in terminal, leafy racemes. The flowers are violet, strongly zygomorphic, of gullet type, with a pair of posterior pockets. Each pocket contains a patch of oil-producing glandular hairs (elaiophore). The flowers were only visited, and pollinated, by oil-collecting female bees of the Apidae-Apinae: Centris hyptidis and Tapinotaspis spec. nov. 1. These two bees differ considerably in size but they share the peculiarity of possessing one pair of disproportionately elongate legs suitable to gain access to the concealed elaiophores. In C. hyptidis, it is the front pair, whereas in T. spec. nov. 1 the mid pair of legs is elongated. T. spec. nov. 1 exhibited two modes of visiting behaviour. Angelonia cornigera is self-incompatible; it does not set fruits from spontaneous or manual self-pollination. This is the fifth observed species of the genus Angelonia whose flowers are adapted to oil-collecting bees in the Caatinga formation. Its flowers deviate in several aspects from the other studied Angelonia spp. regarding pollination relationships. New data on A. hirta and A. tomentosa are appended.