Bulbs and Corms and Tubers, Oh My!

J. Agoston agoston.janos123@gmail.com
Mon, 14 Dec 2009 14:51:21 PST

Erythronium has bulb, and Polygonatum has rhizome, Calla
(Zantedeschia) has tuber, and Ranunculus asiaticus has tuberous root
system. Otherwise your summary is correct.

Z5a, Hungary

2009/12/14 Judy Glattstein <jgglatt@gmail.com>:
> Here is the relevant handout material from back when I taught a required
> bulb i.d. course for School of Professional Horticulture students at the
> New York Botanical Garden:
> Geophytes - definitions
> common point: the ability to store food over adverse conditions.
> bulb: a true bulb is composed of modified leaves called scales. They may
> be loose and open (as in lilies) or tight and compact (as in narcissus).
> Some bulbs have a thin papery covering, called a tunic, as in tulips.
> Roots grow from a basal plate located at the bottom of the bulb. In
> autumn true bulbs contain the embryo plant complete with flower buds.
> True bulbs form offsets from lateral buds on the basal plate.
>    Examples: allium, fritillaria, galanthus, lily, narcissus, tulip, scilla
> corm: a corm is a mass of undifferentiated storage tissue derived from
> modified stem growth and covered by dry leaf bases. These coverings may
> be reticulated (netted) or annulate (ringed). Roots grow from a basal
> plate. The growing points on top may be single or multiple. A new corm
> is formed each year.
>    Examples: colchicum, crocus, erythronium, freesia, gladiolus
> tuber: a tuber is a solid mass of stem tissue, like a corm, but lacks
> the tunic-like covering and basal plate. Roots and shoots arise from
> growing points or eyes scattered over the tuber.
>    Examples: anemone, caladium, cyclamen, eranthis, ranunculus
> tuberous root: similar in appearance to tubers but composed of root
> tissue, not stem tissue. Fibrous roots are produced during the growing
> season, and new growth buds arise at the base of the old stem.
>    Examples: alstromeria, begonia, dahlia, polygonatum
> rhizome: composed of swollen stem tissue, growing laterally at or just
> below the surface, generally freely branching. Roots develop on the
> lower surface, shoots on the top.
>    Examples: calla, canna, convallaria, rhizomatous iris
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