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Wärmeentwicklung von Philodendron Blüten
... Im allgemeinen wird Thermogenese innerhalb eines Blütenstandes als Lockmittel für spezifische Bestäuber angesehen, wobei die erhöhte Temperatur vor allem zur Verbreitung der Geruchsstoffe dient (KNOLL 1926, GOTTSBERGER 1986. Ein weiterer Zusammenhang besteht mit der Bildung der Duftstoffe, die bei Araceen oft mit dem Tag-Nacht-Wechsel einhergeht, zumindest bei A. titan um aber autonom ist (v AN DER . ...
... Für Philodendron selloum ist eine wesentliche Beteiligung von Lipiden bei der Wärmeproduktion während der Anthese nachgewiesen , GOTTSBERGER 1986 Der Geruch von A. titanum kann so penetrant werden, das Gärtner nach dem Gießen der Pflanze die Kleidung wechseln mußten . Je nach Exemplar kann die Geruchsentwicklung aber auch fast völlig unterbleiben . ...
Floral thermogenicity, which is found in several representatives of half a dozen angiosperm families, is most pronounced in the Araceae. It is based on the operation of an alternative, cyanide-resistant electron transport chain which, in contrast to the classic cytochrome oxidase system, produces little ATP; most of the energy originally locked up in the respiratory substrate usually starch — is therefore liberated in the form of heat. The biological function of this (biochemically wasteful) system is to release the heat to serve as a volatilizer for the floral odors (often containing aliphatic amines, indole and skatole) that attract the insect pollinators. This makes the survival value of thermogenesis (for the plant species) immediately clear. Thermogenicity is under tight biological control, as demonstrated by the fact that the same ceiling temperature is always reached, regardless of ambient temperature. In Eastern skunk cabbage (Symplocarpus foetidus), which flowers very early in spring, that ceiling is about 20 C, in tropical forms such as Xanthosoma robustum and Philodendron selloum, it lies in the 42–44 C range. In several instances, e.g., in Arum and in Sauromatum, the voodoo lily, thermogenicity manifests itself as a flare-up of only a few hours' duration, a respiratory explosion that can lead to rates of metabolism that compare favorably with those of a hovering hummingbird. The metabolic peak is always reached at a particular time of day, which is different for the different arum lily species, and thus reduces competition for pollinators. The odors that accompany the heat are also very characteristic, appealing to different pollinator classes and further reducing such competition. In the voodoo lily and in Arum, the primary site for the production of both heat and odor is the naked appendix of the inflorescence, which acts as a specialized osmophore or odor carrier. The first explosion may be followed by another one several hours later, which manifests itself in the floral chamber of the inflorescence and is under strict photoperiodic control. In Sauromatum, the first metabolic explosion is triggered by a plant hormone, originally referred to as calorigen, which originates in the primordia of the staminate flowers and moves from there into the appendix where it exerts its action after a lag-time of about a day — an indication that synthesis of new enzymatic protein (through unblocking of certain genes?) may well be involved. In 1987, calorigen was shown to be identical with salicylic acid. This compound was already known to induce flowering in certain duck-weeds, Lemnaceae, which until recently were regarded as belonging to the same family as arum lilies. In certain water lilies (Nymphaeaceae), thermogenicity is combined with a pollination syndrome very similar to that of Arum and Sauromatum but involving temporary trap flowers.
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