The Diascia (Scrophulariaceae) window: an orientation cue for oil-collecting bees.
01 Feb 1990-Botanical Journal of the Linnean Society (Blackwell Publishing Ltd)-Vol. 102, Iss: 2, pp 175-195
TL;DR: Observations in natural and experimental situations suggest that the window of Diascia section Racemosae is used as an orientation cue by oil-collecting bees.
About: This article is published in Botanical Journal of the Linnean Society.The article was published on 1990-02-01. It has received 22 citations till now. The article focuses on the topics: Ultraviolet light.
Citations
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126 citations
TL;DR: Investigation of epidermal cell shape and pigmentation on tissue optical properties in the visible and ultraviolet (UV) spectral regions of Antirrhinum majus found that intact Mixta+ flowers reflected less light in the spectral regions with intermediate flavonoid absorbance than intact mixta- flowers.
Abstract: We used the Mixta+ and mixta- lines of Antirrhinum majus as a model system to investigate the effects of epidermal cell shape and pigmentation on tissue optical properties in the visible and ultraviolet (UV) spectral regions. Adaxial epidermal cells of Mixta+ flowers have a conical-papillate shape; in the mixta- line the cells are slightly domed. Mixta+ cells contained significantly more anthocyanin and other flavonoids than mixta- cells when plants were grown under either high- or low-UV conditions. Mixta+ cells focused light (3.5-4.7 times incident) within their pigmented interiors, whereas mixta- cells focused light (2.1-2.7 times incident) in the unpigmented mesophyll. UV light penetrated the epidermis (commonly 20-50% transmittance at 312 nm) mainly through the unpigmented peripheral regions of the cells that were similar for the two lines, so that overall penetration through Mixta+ and mixta- epidermises was equal. However, maximum UV absorption in the central region of epidermal cells was slightly greater in Mixta+ than mixta-, and intact Mixta+ flowers reflected less light in the spectral regions with intermediate flavonoid absorbance. In both cases, about 50 to 75% of the difference could be attributed to cell shape and resulting changes in the optical pathlength or focusing.
125 citations
TL;DR: The flowers of the Scrophulariaceae show a great diversity in form, especially of the corolla, and their diversity of forms exemplifies the evolutionary potential of fused perianth parts.
Abstract: The flowers of the Scrophulariaceae show a great diversity in form, especially of the corolla. The most common pollinators are bees collecting nectar, pollen, or oil; other pollinators are moths and butterflies, hummingbirds, syrphid flies, and (in one case) ants. The occurrence of bell-shaped corollas in most tribes of the Scrophulariaceae and in related families indicates that this is the basic (ancestral) flower form. Derived from it are narrow tubular corollas, wide flaring ones, corollas closed to unsuitable visitors by a palate (an upcurving of the tube), corollas forming a keel around the style and anthers either on the upper or lower side of the flower, corollas inflated to form a balloon, and corollas with one or two spurs. Convergences due to selection by the same or similar pollinators limit the usefulness of most of these floral features in analyzing the systematic relationships of the tribes of the Scrophulariaceae. Nevertheless, their diversity of forms exemplifies the evolutionary potential of fused perianth parts.
65 citations
TL;DR: As more work on pollination is done in Africa, more differences between African systems and the rest of the world, particularly the North temperate regions will be found and changes to the overall conceptualization of pollination systems in different ecosystems are likely to ensue.
Abstract: The literature on African pollination biology is reviewed. It is found that relatively little work has been done on pollination biology in Africa, and a very small proportion of pollination relationships has so far been studied. Much of the research which has been done is of an evolutionary nature. Very little work has been conducted at the community level and comparatively little applied work, either to agriculture or conservation, was encountered. Most research has been conducted in South Africa, in particular, from the Cape region, which is the only part of Africa for which a reasonably comprehensive body of work on pollination biology exists. In a number of instances results of African studies challenge conventional understanding of pollination biology. It is argued that as more work on pollination is done in Africa, more differences between African systems and the rest of the world, particularly the North temperate regions will be found and changes to the overall conceptualization of pollination systems in different ecosystems are likely to ensue. A more thorough understanding of pollination biology would also make an important contribution to food security and conservation of biodiversity on the continent. Scientists working in fields other than pollination biology, and amateurs, should be encouraged to contribute to the groundwork of African pollination biology by the documentation of pollination relationships.
61 citations
01 Dec 2006
TL;DR: The aim of this review is to illustrate the various cases in which flowering plants may benefit from attracting flower-visitors by means of mimic stamens.
Abstract: Lunau, K.: Stamens and mimic stamens as components of floral colour patterns. — Bot. Jahrb. Syst. 127: 13–41. 2007. — ISSN 0006-8152. Dedicated to Professor Dr. Gunther Osche, Freiburg im Breisgau (Germany), on the occasion of his 80th birthday; he discovered the phenomenon of mimic stamens when re-assessing floral colour pattern with his eyes newly tuned by Wicklerian thoughts about automimicry. Stamens of zoophilous plants are multifunctional floral organs which protect pollen against environmental stress, attract potential pollinators, attach pollen to the sites of secondary pollen presentation, or to the pollinator’s body surface, and provide pollen as a reward for flower-visitors. Pollen-eating flower-visitors such as syrphid flies and pollencollecting flower-visitors such as bees innately respond to visual and chemical cues of stamens and pollen prior to individual experience. Flowering plants presenting conspicuous stamens and pollen to attract pollinators incur numerous costs associated with visual exposure of pollen including investments for protection against solar radiation, pollen losses caused by wind, rain, and illegitimate flower-visitation, and pollen losses due to consumption of pollen by flower-visitors or pollinators. Many flowers use mimic stamens (e.g. staminodes, false stamens, yellow floral guides in the size and shape of anthers) and thus overcome these disadvantages. Several study cases focus on the benefits of signaling with mimic stamens in flowering plants having polymorphic flowers, distinct flowering phases, and hidden real pollen. The aim of this review is to illustrate the various cases in which flowering plants may benefit from attracting flower-visitors by means of mimic stamens.
55 citations
References
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TL;DR: Petal structure and the distribution of pigments in petals were studied in relation to the functional anatomy of petals and the ways in which petals absorb and reflect light.
291 citations
DOI•
01 Sep 1956TL;DR: In this paper, the Bienensinn der Bienen is wesentlich leistungsfahiger, d. h., die Zahl der unterscheidbaren Farbtone is a groser als bisher angenommen: Auch innerhalb der Kuhnschen Hauptspektralbereiche, deren Existenz bestatigt wurde, sind die bienen zu echter Wellenlangenunterscheideung befahigt.
Abstract: Der Farbensinn der Bienen ist wesentlich leistungsfahiger, d. h., die Zahl der unterscheidbaren Farbtone ist groser als bisher angenommen: Auch innerhalb der Kuhnschen Hauptspektralbereiche, deren Existenz bestatigt wurde, sind die Bienen zu echter Wellenlangenunterscheidung befahigt. Der Farbton andert sich dabei innerhalb der zwei schmalen Spektralbereiche des Blaugrun und des Grenzbereiches Violett-UV relativ wesentlich mehr als innerhalb der drei breiten Spektralstrecken des Gelb-, Blau- und UV-Bereiches. Uber eine Reihe gut unterscheidbarer Gelb + UV- „Purpur“ tone (den Bienen-Purpurbereich) schliest sich das Bienenspektrum zum Farbenkreis. Dieses Ergebnis stutzt die Vermutung, das auch das Farbsystem der Bienen mindestens trichromatisch ist.
218 citations
DOI•
01 Jan 1958TL;DR: In this paper, a quantitativ auswertbaren, fotografischen Methode in den 3 Grundspektralbereichen des Bienenfarbsystems (Gelb-, Blau-and UV-Bereich) gestattete auf Grund der Kompensativbeziehungen zwischen diesen Bereichen (Daumeb 1956) die ungefahre Berechnung von „BienenFarbton“ and „Unbunt
Abstract: 1.
Die Bestimmung der Reflexion von Bluten mittels einer quantitativ auswertbaren, fotografischen Methode in den 3 Grundspektralbereichen des Bienenfarbsystems (Gelb-, Blau- und UV-Bereich) gestattete auf Grund der Kenntnis der Kompensativbeziehungen zwischen diesen Bereichen (Daumeb 1956) die ungefahre Berechnung von „Bienenfarbton“ und „Unbuntanteil“ von Bluten und Blattern in Gestalt charakteristischer Kennzahlen.
2.
Fur 204 Bluten und 60 Blatter verschiedener Arten wurden mit den gemessenen Reflexionsdaten diese Kennzahlen berechnet und die Bluten in der Reihenfolge ihrer „Bienenfarbtone“ im „Bienenfarbkreis“ angeordnet. Die Einteilung dieser Blutenreihe in Gruppen unterscheidbarer „Bienenfarbtone“ (Tabelle 1–10) erfolgte auf Grund der Versuche uber die Wellenlangenunterscheidung von Spektrallichtern am Spektralfarbmischapparat. Als Ergebnisse konnen festgehalten werden:
3.
Die Vielzahl der dem Menschen gelb (orange, gelbgrun) erscheinenden Bluten bietet sich den Bienen auf Grund sehr verschiedener UV-Reflexion in drei vollig verschiedenen Farbtonen: „Bienengelb“ (Tabelle 1a und b), „Bienenpurpur“ I (Tabelle 2) und „Bienenpurpur“ II (Tabelle 3). Vgl. dazu Abb. 12a–c, S. 77.
4.
Die vielen dem Menschen weis erscheinenden Bluten, daneben grunliche, rosa und lila Bluten, sind fur die Bienen infolge Reflexion im Gelb- und Blaubereich und starker Absorption im UV-Bereich „Bienenblaugrun“ (Tabelle 4). Vgl. dazu Abb. 7, S. 66.
5.
Unter den dem Menschen blau und violett erscheinenden Bluten herrscht eine so grose Mannigfaltigkeit in der UV-Reflexion, das die Bienen diese Bluten in nicht weniger als vier vollig verschiedenen Farbtonen sehen: „Bienenblau“ I (Tabelle 5), „Bienenblau“ II (Tabelle 6), „Bienenviolett“ I (Tabelle 7) und „Bienenviolett“ II (Tabelle 8). Vgl. dazu Abb. 14, 15, S. 79 und 80.
6.
Die roten Bluten erscheinen den Bienen je nach dem Grad der UV-Reflexion entweder „Bienenultraviolett“ (Tabelle 9) oder (selten) „Bienenschwarz“ (Tabelle 10). Vgl. dazu Abb. 8, 9, S. 71.
7.
Infolge schwacher, relativ gleichmasiger Reflexion in allen Bienenspektralbereichen erweisen sich die grunen Blatter als „Bienengrau“ mit schwachem Farbstich ins „Bienengelb“, so das sich die Bluten als bunte Farbflecken vom mehr oder minder unbunten Hintergrund gut abheben mussen. Vgl. dazu Abb. 3, S. 54.
8.
Dressurversuche mit gelben („bienengelben“ und „bienenpurpurnen“) sowie mit blauen („bienenblauen“ und „bienenvioletten“) Bluten zeigten, das die Bienen tatsachlich in der Lage sind, dem Menschen gleichfarbig erscheinende Bluten auf Grund verschieden starker UVReflexion sehr gut zu unterscheiden, in Bestatigung der Brauchbarkeit der vorgenommenen Einteilung der Bluten nach „Bienenfarbtonen“.
9.
Die Blutenaufnahmen im UV-Bereich forderten eine Reihe von herrlichen, dem unbewaffneten menschlichen Auge unsichtbaren Reflexionsmustern von Saftmalcharakter zutage. Ihre Ausbildung last einen engen Zusammenhang mit dem Blumentyp und der Statte der Nektar- und Pollenproduktion erkennen. Diskussion der Ergebnisse s. S. 93.
10.
Dressurversuche mit UV-gemusterten Bluten erbrachten den Nachweis fur Sichtbarkeit und Auffalligkeit der UV-Muster. Aus einem typischen Verhalten der Bienen gegenuber Bluten-UV-Mustern (Kopf-Russel-Reaktion) geht ihre Bedeutung als Wegweiser zum Nektar hervor, so das sie als Saftmale bzw. Pollenmale bezeichnet werden konnen.
11.
Versuche mit blutenunerfahrenen, undressierten Bienen erwiesen die Kopf-Russel-Reaktion auf diese Saftmale als angeboren. Diskussion der Ergebnisse s. S. 106.
177 citations
TL;DR: Evidence is presented that discrimination occurs because white flowers have inferior ‘nectar guides’ and therefore require longer handling times than blue flowers, and pollinators may experience lower net rates of energy intake on white flowers, a sufficient reason for undervisitation by optimally-foraging animals.
Abstract: Evolutionary biologists continue to disagree about the relative importance of natural selection, drift and phylogenetic constraint in determining characteristics of an organism1. Because of the difficulty of identifying examples of selection in nature there are few rigorous field studies of selection2–6. We have been studying selection on flower colour in the small perennial larkspur Delphinium nelsonii, a native to mountains of the western USA. Previously we showed that white-flowered forms, which are very rare in natural populations, produce fewer seeds than their common blue-flowered conspecifics, and that this selective disadvantage results from partial discrimination against white flowers by bumblebee and hummingbird pollinators7. Here we present evidence that discrimination occurs because white flowers have inferior ‘nectar guides’ and therefore require longer handling times than blue flowers. Pollinators may thus experience lower net rates of energy intake on white flowers, a sufficient reason for undervisitation by optimally-foraging animals.
148 citations
TL;DR: Morphological and physiological changes in the floral colour patterns of both species following pollination appear to inhibit visitation by bees, and the significance of U.V. floral patterns was also considered.
102 citations