Bravo! It's gratifying to know that those definitions haven't changed in six decades; those are the same definitions I learned as a child in High School. But then again, I went to school in New York. David E. ________________________________ From: Judy Glattstein <jgglatt@gmail.com> To: pbs@lists.ibiblio.org Sent: Mon, December 14, 2009 1:45:14 PM Subject: [pbs] Bulbs and Corms and Tubers, Oh My! 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