EARLY CROCUS

Crocus tommasinianus

Iris Family [Iridaceae]  

month8Feb month8mar month8march month8apr month8april

status
statusZneophyte
flower
flower8lilac
inner
inner8yellow
morph
morph8actino
petals
petalsZ6
stem
stem8round

10th February 2008. Photo: © RWD
Growing amidst Woodruff. Crocuses have three outer tepals and three concolorous inner petals.


10th February 2008. Photo: © RWD
The tubular stem is white. [Montbretia in background].


10th February 2008. Photo: © RWD
The grass-like leaves are narrow and have a light-green coloured central spine.


10th February 2008. Photo: © RWD


10th February 2008. Photo: © RWD
Three paler yellow stamens surround a shorter tri-forked feathery orange stigma.


Easily confused with : Spring Crocus except that Early Crocus flowers up to a month earlier.

Some similarities to Tulips such as Wild Tulip (Tulipa sylvestris) with 3 tepals and 3 petals.

Early Crocus is a neophyte; there are no native Crocuses in the UK.

THERMONASTY in TULIP & CROCUS flowers

Crocuses exhibit a phenomena called Thermonasty, which is the method by which they are able to open up in the daylight and close up at night. Tulips also exhibit this characteristic too.

Like a bimetallic strip, it is based upon rising and falling temperatures, but un-like bimetallic strips, it is not due to any differential thermal expansion nor to ordinary thermal expansion. The tepals are able to sense temperature, and when they are warming up (sun rising) the tepals grow differentially more on the inside of the tepal than they do on the outside. This differential growth forces the tepal to open outwards. A temperature increase of only 0.36°C is sufficient to initiate the opening of the flowers.

Conversely, as the temperature drops, it is the outer parts of the tepal which grow faster than the inner parts, forcing them to close again. Note that the tepals can only grow bigger, they cannot 'grow shorter'. Tulips also exhibit thermonasty.

This differential growth rate is due to the cells on the inner surface of tepals having an optimum growth rate that is 10°C higher than the cells on the outer surface of the tepals. This difference in growth rate is due to differences in the internal carbon dioxide concentrations. Increasing the concentration of CO2 causes a marked extension in the cells and a lowering in the temperature for optimum growth. The effect is thus closely related to the plants respiration.

It does this to protect the pollen within from rain or snow.

Other flowers accomplish the opening and closing of flowers or other parts of the plant by differing means, such as by either Tropic movements or by Nastic movements. Nastic movements are initiated by various stimuli, thus Chemonasty is initiatated by soil chemicals or nutrients, Epinasty (by gravity), Geonasty (by gravity), Hydronasty (by water), Hyponasty (by the growth hormone Ethylene), Nyctonasty (by circadian clock and light), Photonasty (by light), Thermonasty (by heat) and Thigmonasty (by touch).


  Crocus tommasinianus  ⇐ Global Aspect ⇒ Iridaceae  

Distribution
family8iris family8Iridaceae

 BSBI maps
genus8crocus
Crocus
(Crocuses)

EARLY CROCUS

Crocus tommasinianus

Iris Family [Iridaceae]  

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