Cactaceae

CACTUS
   
 cactus classification : 
Classification of Cacti:
Kingdom - Plantae (plants) Phylum - Tracheophyta (vascular plants) Division - Magnoliophyta = Anthophyta] (angioperms) Class - Dicotyledonae = Magnoliopsida (dicots) Subclass - Caryophyllidae Order - Caryophyllales Family - Cactaceae (cacti) Genus - About 100 genera and 1000-2000 species divided into three tribes 


life cycle of a cactus


the character of cactus
 Cacti occur in a wide range of shapes and sizes. Most cacti live in habitats subject to at least some drought. Many live in extremely dry environments, even being found in the Atacama Desert, one of the driest places on earth. Cacti show many adaptations to conserve water. Almost all cacti are succulents, meaning they have thickened, fleshy parts adapted to store water. Unlike many other succulents, the stem is the only part of most cacti where this vital process takes place. Most species of cacti have lost true leaves, retaining only spines, which are highly modified leaves. As well as defending against herbivores, spines help prevent water loss by reducing air flow close to the cactus and providing some shade. In the absence of leaves, enlarged stems carry out photosynthesis.

uniqueness of cactus 

Size of cactus depends on the species. Largest species of cactus can reach 66 feet in height and weigh up to 4800 pounds (when it is fully loaded with water). Smallest species usually have only few inches in height.

Cactus can have arborescent (tree-like), cylindrical, rounded, irregular or starfish shape. Surface can be flat or covered with ridges.

Cacti can be green, bluish or brown-green in color. They have waxy substance on the surface which prevents loss of water via transpiration (loss of water through small holes when outer temperature is high).

Cacti have spines instead of leaves. Spines can be soft or rigid, straight or curved, arranged in rows or scattered. They can reach 6 inches in length.

Spines have two major roles: they prevent loss of water via transpiration and keep the plant safe from animals.

Each spine develops from areole, which looks like a bump or nipple-like structure on the surface of the cactus.

Since cacti live in dry areas, they need to absorb large amount of water and store it in the stem and roots for the periods of drought. Besides storing of water, stem plays role in the process of photosynthesis (production of food by using the sunlight and carbon dioxide).

Water from cactus has higher density compared with tap water, but it is safe for drinking.

Roots of cacti are located few inches underground, but they can reach 7 feet in diameter because water easily passes through the sand.

Cacti have dormant periods and periods of intense growth and blossoming. Periods of growth require enough water and sunlight and they usually last shorter than periods of rest.

Size and shape of flower depends on the species of cacti and type of pollination. They can be white, red, orange, pink or blue in color.

Butterflies, bees, moths, bats and hummingbirds are main pollinators of cacti.

Spines of cactus can be used in the production of hooks, combs and needles. Fruit can be used as food.

Certain cacti produce substance called mescaline which induces hallucinogenic effects. It has been used by shamans to induce trans-like state and ensure "communication" with God.

Cacti can survive from 15 to 300 years, depending on the species. Question 1. What is cactus? 2. What is the function of spines in cactus? 3. Where cactus lives? 4. How long cactus can survive? 5. What is cactus classification?