AY Honors/Cacti - Advanced/Answer Key

1. What are succulents?

Succulent plants, also known as succulents or fat plants are water- retaining plants adapted to xerophilic climatic or soil conditions. Succulent plants store water in their leaves, stems and/or roots. The storage of water often gives succulent plants a more swollen or fleshy appearance than other plants, also known as succulence. In addition to succulence, succulent plants variously have other water-saving features.

3. Know the definitions of the following terms within a cacti/succulents frame of reference.

a. Areole

Areoles are the distinctive feature of cacti, and identify them as a separate family from other succulent plants.

b. Cephalium

Cephalium is a frequently brightly colored, structure of wool and bristle at the growing tip of certain cacti. It is most commonly found on cacti of the genus Melocactus and can take a number of colors, forms and shapes.

c. Coalesce

d. Corymb

A corymb is similar to a panicle with the same branching structure, but with the lower flowers having longer stems, thus giving a flattish top superficially resembling an umbel.

e. Diurnal

A plant or animal that is active in the daytime

f. Epiphyte

An epiphyte is an organism that grows upon or attached to a living plant.

g. Glochid

Glochids are tiny, almost invisible barbed hairs found on the areoles of some cacti and other plants.

h. Nocturnal

Primarily active during the night.

i. Offshoot

Offshoots are lateral shoots that are produced on the main stem of a plant.

j. Panicle

A panicle is a compound raceme, a loose, much-branched indeterminate inflorescence with pedicellate flowers (and fruit) attached along the secondary branches (in other words, a branched cluster of flowers in which the branches are racemes).

k. Scale

Scale are small insects of the order Hemiptera, most of which are parasites of plants, feeding on sap drawn directly from the plant's vascular system.

l. Stolon

A stolon, commonly referred to as a runner, is an aerial shoot from a plant with the ability to produce adventitious roots and new clones of the same plant.

m. Zygomorphic

having bilateral symmetry

4. When raising succulents — including cacti — they may be attacked by maladies. What are the most common and how can you prevent or cure the problems?

The most common cactus malady is mold, usually caused by overwatering. If mold is detected on a cactus, the affected part should be cut off as soon as possible, using a sharp knife. Then the wound should be sprinkled with sulphur or a fungicide. If the roots are affected, the core of the cacti is probably also affected and the plant will almost certainly die.

The only pests that bother cacti are a type of scale insect of the family Coccoidea, and nematodes. Scale insects may be killed by squirting the plant with a mixture of rubbing alcohol and nicotine. If nematodes are detected, the roots of the cactus must be cut off with a sharp knife and the plant repotted in sterile soil until it grows new roots. The old soil should be sterilized and the removed roots should be burned.

References

• http://users.lycaeum.org/~iamklaus/grow.htm