When Arum Flowers Run Hot

Cooke drew attention to a curious warmth in flowering aroids, plants whose many small flowers crowd around a central spike called a spadix. An enclosing leaf-like spathe surrounds the flowers and, he wrote, slows the escape of heat, making the rise easier to detect^[1].

The temperatures were reports from observers Cooke cited, not measurements he claimed as his own. Sennebrier reported 86°C in the common arum; Hubert placed a thermometer among five spadices of another arum and recorded 131°F, then 142½°F among twelve, while the air was 74–75°F^[2]. Cooke interpreted the warmth as heat released by oxidation and chemical changes during flowering. That was his historical explanation, rather than a modern mechanism established by these observations alone^[3].