February 2010

What is a bulb? Never gave it much thought until the subject came up in Flower Show Judge school.

1. True Bulbs – The true bulb has five major parts. It contains the basal plate (bottom of bulb from which roots grow), fleshy scales (primary storage tissue), tunic (skin-like covering that protects the fleshy scales), the shoot (consisting of developing flower and leaf buds), and lateral buds (develop into bulblets or offsets). There are two different kinds of true bulbs:
– Tunicate: bulbs shred or peel off layers (tunicate layers) – daffodils, onions
– Scaly: individual toes that sprout and can be planted individually – garlic is a great example of this.

2. Stem Tuber – made up of nodes and internodes, does not have a basal plate and does not have a protective tunic covereing. Buds appear all over the surface of a tuber, then develop into stems and roots. Irish potatoes are a perfect example of this, as are anemones and oxalis.

3. Tuberous Roots – actually store nutrients in their roots instead of enlarged stem. Buds develop at the top of the root. Examples of tuberous roots include sweet potato and dahlias.

4. Rhizome – grows horizontally under ground. Lots of grasses develop this way, as well as iris. Rhizomes are infamous for being invasive and spreading like wildfire.

5. Corm – is a compressed bulb, very similar to true bulbs in that they have a basal plate and a protective tunic skin, but the major difference is that there are no visible storage rings if you cut it in half. Examples are watsonia and gladiolus.

Alright, now plant those summer bulbs!

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