Smells Like Pollination

Arum maculatum

 April, and as the days get warmer, plants and animals are shaking off the last of the lethargy of winter. As insects become more populous, plants vie for their attention to be pollinated. Timing for this is often essential, as can be seen in the case of the Lords and Ladies (or Cuckoo's Pint, Arum maculatum).This perennial plant emerges from underground tubers in late winter/early spring in shaded woodlands and hedgerows, with striking pale green flowers arriving in April to May (1). In a study of four populations of the plant over five years in Northampton found that plants flowering during late and early periods were more likely to have less fruit than those flowering during peak time (2). Indeed, the seeds for peak flowering plants were significantly heavier than those from other times. Pollination of A. maculatum is achieved principally by the psychodid midge or moth fly Psychoda phalaenoides which is attracted to the flowering plant by a cocktail of volatiles emitted from the spadix appendix and the spathe chamber (3). The attracted P. phalaenoides becomes trapped by the the flower and is released a short time later. During this time pollination is achieved.

Psychodid midge

Interestingly the volatiles emitted by the flower to attract its pollinator, specifically p-cresol, ingenuously mimic those of cow dung, the microhabitat for P. phalaenoides. This duping of the insect is of obvious advantage to the plant but is not mutualistic. The insect receives no food for its interaction and indeed has wasted a considerable part of its short life (4).

References:

1. Phillips, 1978. Wildflowers of Britain and Ireland
2. Ollerton and Diaz, 1999. Oecologia 119 pp. 340-348
3. Kite, 1995. Biochemical Systematics and Ecology 23 pp. 343-354
4. Urru, 2011. Phytochemistry, Article in Press