Alpine Garden Society

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Botany Introduction

What follows is an introduction to the botany of the Crocus. A quick perusal of the terms used will help in understanding (and enjoying) the many images on the site.   A basic knowledge of the botany of the plant is more essential if you are hoping to use the site to identify plants seen in the wild or grown at home.

The Crocus is a perennial plant, with an underground storage organ in the form of a corm, which has evolved to overcome a dry period during which the plant is dormant.   They are dwarf plants, the flowers rarely exceeding 15cm (6 inches) although the leaves may be considerably longer.  

Crocus corms vary considerably in size and shape.   The corm tunic, the outer coat of the corm, which is formed of expanded leaf bases, also varies considerably.   This can be a helpful diagnostic feature.    Tunics may be papery, fibrous or eggshell-like. Fibrous tunics may have parallel fibres, be interwoven or reticulate (netted).  

Above ground almost all species have leaves with a distinctive central white stripe, which is due to some cells having no chlorophyll.   Flowers develop on a tube, the true stem remaining below ground until the seeds ripen.   Flowers have six petals in two whorls of three, the outer set often slightly larger, can also be attractively marked.   Colour varies greatly through a common theme of white, yellow and purple, in many shades and combinations.   Crocuses have three stamens.   The pollen bearing anthers may be yellow, white or black and are attached to the throat of the flower by short stalks called filaments.   White anthers have white pollen but black anthers open to reveal golden pollen as do yellow anthers.   The style extends from the centre of the flower, between the anthers.   It divides into three or more branches, at the tips of which are the pollen-receiving stigma.   The type of branching and its extent can be an important aid in distinguishing between species, as well as often being a very attractive feature.   Pollination is achieved by insects; bees, moths and beetles.   Many species have a delicious honey scent.

The seeds ripen as the leaves die away.   The subterranean ovary is pushed up as the stem below lengthens, thus the developing seeds are protected from adverse weather and grazing until ripe for dispersal.   A completely new corm develops on top of the old one during each growing season.

  • Corms and Tunics
  • Leaves
  • Flowers
  • Stamens and Styles
  • Pollination and Seeds