Thermogenesis in four species of Schismatoglottis Calyptrata Clade (Schismatoglottideae: Araceae)

Abstract

Spadix temperature was measured in Schismatoglottis ahmadii, S. lowiae, S. sp. nov., and S. wallichii. The anthesis of S. lowiae, S. sp. nov., and S. wallichii started just after dawn but in S. ahmadii, it began two hours later. Spadix temperatures of the four species increased at the beginning of each of the two successive flowering mornings, corresponding respectively to the pistillate and staminate phases of anthesis. The appendices of S. ahmadii, S. lowiae, and S. sp. nov. underwent the highest temperature increases (average 9.5°C above ambient air) compared to the staminate zone (6.5°C above ambient air); almost no thermogenic activity was recorded in the pistillate zone (0.4°C above ambient air). In inflorescences of S. wallichii, in which the spadix lacks an appendix, the pistillate zone also heated up (2.3°C above ambient air), together with the sterile (2.6°C above ambient air) and the staminate zones (5.2°C above ambient air). Thermogenic patterns varied across species owing to differences in timing of anthesis or spadix structures. The absence of an appendix (sterile floral tissue) in S. wallichii, is not only partially compensated by heat production from the (intermediate) sterile zone but also heat production from the pistillate zone, recorded here for the first time in Tribe Schismatoglottideae.