Updated: February 11, 2014 @ 11:20am local time. The name updated on February 6 is now accompanied by an updated written entry — Daniel
This is the second entry in the series about nastic movements in plants.
Today’s intensely purple photo is of a cultivar of Crocus tommasinianus, most likely ‘Ruby Giant’ (see comments below). Previously, the taxon in the image was believed to be an unidentified cultivar of Crocus vernus, but with input from BPotD readers, it has been changed to reflect their collective knowledge. Crocus tommasinianus is commonly known as the woodland crocus, the early crocus, or Tommasini’s Crocus (after the Italian botanist, Muzio G. Spirito de Tommasini).
For many, the sight of Crocus is a sign that spring is on the way! Crocus tommasinianus, like many (all?) other ninety or so species in the genus, is thermonastic, meaning it has a movement in response to temperature. Flowers open and may even close in response to spring’s changing temperatures. As an example of how sensitive these flowers are to fluctuating temperatures, Crocus vernus (thought to be the most sensitive species in the genus to temperature changes) has been observed to have its flowers triggered to open with a rise in temperature of only 0.2 degrees Celsius (see: Andrews, FM. 1929. The effect of temperature on flowers (PDF). Plant Physiology. 4(2):281-284).
Crocus tommasinianus is native to southern Hungary, north west Bulgaria, Bosnia, and Herzegovina. This early-blooming crocus may bloom in autumn, but most commonly flowers in early spring. When the goblet-shaped flowers of purple tepals open, the tepals are contrasted by yellow-orange stamens and an orange-red style, as shown by Stephen’s photograph.