Floral temperatures of the southern-most flowering Amorphophallus titanum and seedling growth following self-pollination

Amorphophallus titanum (Becc.) Becc. (Araceae) is native to the rainforests of Sumatra, and famously produces a single, massive, thermogenic and highly odoriferous inflorescence. Despite having both male and female flowers in close proximity, A. titanum does not readily self-pollinate as it is strictly dichogamous, with female flowers receptive on the first night of flowering and pollen released on the second night. We report on external and internal temperatures reached by the most southerly plant in cultivation which flowered in February 2018 in Dunedin, New Zealand. We also report on successful self-pollination of the same plant in January 2021 with pollen collected in 2018 that had been stored at -80˚C. External spathe and internal spadix temperatures exceeded ambient temperatures on both flowering nights in 2018. Self-pollination in 2021 resulted in copious fruits that matured in 8 months and showed 75% germination success. More than a fifth of all seedings to germinate were achlorophyllous and died within four months, which is consistent with inbreeding depression. Seedling height, leaf production, length of active growth period and corm size varied markedly among the surviving chlorophyllous seedlings, with some producing two leaves in their first year. While we would not recommend the use of self-pollination for propagation of this species due to the likely presence of inbreeding depression, our study does prove that pollen can retain its viability at -80˚C for at least several years which is an important step towards a pedigree-informed breeding programme among plants in cultivation.