Thermogenic flowering of the giant taro (Alocasia macrorrhizos, Araceae)

Abstract

The investigations of thermogenesis of Alocasia macrorrhizos (L.) G. Don inflorescences took place from December 2002 to February 2003, and from February 2004 to March 2004, in one of the wild populations on Espiritu Santo, Vanuatu (South Pacific). Temperatures were measured with six Copper-Constantan (type T) infra-millimetric thermocouples wired to a Campbell Scientific 10X data logger. The thermogenic period lasted 36–42 h, and heating was documented on the male part and the sterile appendix. The highest temperatures were recorded on the sterile appendix. They started to rise slightly before midnight and peaked between 0545 and 0600, when the inflorescence odour became the most intense. The average maximum temperature of 59 investigated inflorescences was 43.9 ± 0.6 °C. The absolute maximum was 47.4 °C. The maximum deviation from the ambient air temperature was 25.6 °C. The heating of the male part began 10–15 h before the inflorescence odour became the most intense and ended 2–3 h after the release of pollen. Its temperatures had two peaks: the first one appeared 15 min after the temperature peak of the sterile appendix, whereas the second one appeared at the time of the release of pollen. The dominating visitors of the flowering inflorescences were earwigs (Labidura truncata Kirby, Labiduridae, Dermaptera). Seed set was extremely rare.Key words: giant taro, Alocasia macrorrhizos, thermogenesis, inflorescence development, pollination.

Pollination mutualism between Alocasia macrorrhizos (Araceae) and two taxonomically undescribed Colocasiomyia species (Diptera: Drosophilidae) in Sabah, Borneo

“…Ivancic et al. (2005) studied inflorescence heating (thermogenesis) of A. macrorrhizos in Vanuatu and reported that the average maximum temperature ± SEM of the appendix reached 43.9 ± 0.6 °C (n = 59 inflorescences; average ambient air temperature was 22.4 ± 0.5 °C) between 05:45 and 06:45 h on the first morning of anthesis.…”

“…The Colocasiomyia flies pollinated their host in a sophisticated and effective manner, as has been reported for other pollination mutualisms between Colocasiomyia flies and their species-specific host plants in the Araceae (Carson & Okada 1980;Kramadibrata & Hambali 1983;Mori & Okada 2001;Takenaka 2006;Takenaka et al 2006; see also Cleghorn 1913;Toda & Okada 1983;Yafuso 1993). Ivancic et al (2005) studied inflorescence heating (thermogenesis) of A. macrorrhizos in Vanuatu and reported that the average maximum temperature ± SEM of the appendix reached 43.9 ± 0.6°C (n = 59 inflorescences; average ambient air temperature was 22.4 ± 0.5°C) between 05:45 and 06:45 h on the first morning of anthesis. The function of the inflorescence thermogenesis in Araceae is generally agreed to be to volatilise odour compounds for pollinator attraction (Mayo et al 1997).…”

“…1997). The time of flower visiting by the Colocasiomyia flies observed in the present study corresponded well to the time of the peak temperature reported in Ivancic et al. (2005).…”

How many species of arthropods visit flowers?

“…Itioka et al (2003) showed that the abundance of Blattodea in Borneo increased in the canopy during a mass-flowering event, indicating that some species at least were anthophilous. A few species of stoneflies (Perlidae and Chloroperlidae) have been observed feeding on nectar, while some earwigs (Anisolabidae, Forficulidae) will hide in flowers or feed on pollen and nectar (Porsch 1957;Ivancic et al 2005;Rankin and Palmer 2009). It has been suggested that female Corydalus (Corydalidae) dobsonflies (and perhaps numerous other species) may feed on nectar to aid in the maturation of their eggs (Anderson 2009).…”

Flowering period, thermogenesis, and pattern of visiting insects in Arisaema triphyllum (Araceae) in Quebec

“…Increases in inflorescence temperature have been studied in many genera of Aroideae with unisexual flowers, Alocasia, Arum, Caladium, Colocasia, Dracunculus, Helicodiceros, Homalomena, Philodendron, and in a few genera with bisexual flowers, Anthurium (subfamily Pothoideae), Monstera (subfamily Monsteroideae), and Symplocarpus (subfamily Orontioideae) (Yafuso 1993;Bermadinger-Stabentheiner and Stabentheiner 1995;Seymour and Schultze-Motel 1999;Barabé and Gibernau 2000;Gibernau and Barabé 2000;Barabé et al 2002;Albre et al 2003;Seymour et al 2003;Angioy et al 2004;Ivancic et al 2004Ivancic et al , 2005Seymour 2004;Maia and Schlindwein 2006). Increases in inflorescence temperature have been studied in many genera of Aroideae with unisexual flowers, Alocasia, Arum, Caladium, Colocasia, Dracunculus, Helicodiceros, Homalomena, Philodendron, and in a few genera with bisexual flowers, Anthurium (subfamily Pothoideae), Monstera (subfamily Monsteroideae), and Symplocarpus (subfamily Orontioideae) (Yafuso 1993;Bermadinger-Stabentheiner and Stabentheiner 1995;Seymour and Schultze-Motel 1999;Barabé and Gibernau 2000;Gibernau and Barabé 2000;Barabé et al 2002;Albre et al 2003;Seymour et al 2003;Angioy et al 2004;Ivancic et al 2004Ivancic et al , 2005Seymour 2004;Maia and Schlindwein 2006).…”