Systematics   

  Description   

  Distribution & Habitat   

  Culture   

  Propagation   

  Uses   

  References

  

Scientific Name   

Cereus hexagonus

   

   

Common Name

Crested Cactus

  

   

Taxonomy   

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Kingdom: Plantae

Phylem: Magnoliophyta

Class: Magnoliopsida

Subclass: Caryophyllidae

Order: Caryophyllales

Family: Cactaceae

Genus: Cereus

Speices: hexagonus
 

Reference for Systematics:

 

Diversity and Classification of Flowering Plants By Armen Takhtajan

Description

Cereus hexagonus, a columnar plant, is tall and treelike with a short trunk that may be decades old and consists of fibrous wood. C. hexagonus has thick-jointed stems that branch from the base. The branches and trunk of this crested cactus are deeply four-, five-, or six-ribbed and covered with spines, highly modified leaves or leaf parts. Areoles, the radial arrangement of spines, are arranged in a regular pattern along the ribs of this columnar cactus, approximately 3/4 inch apart. The spines serve several functions. They protect the plant against herbivory as well as slow down blowing winds thus reducing evaporative water losses. Also, the spines serve as a surface upon which the moisture of the cool night air can condense. This condensation then drips to the ground where the roots can absorb it. Though the spines do not photosynthesize, the tropical cactus's bright green epidermal shoot acts as a photosynthetic organ. The trunk consists of columns of cells that barely touch. Each cell is separated by intercellular space that permits the diffusion of carbon dioxide, and the trunk cells are loaded with choroplasts. The cortex of C. hexagonus serves as a site for storage of water. During periods of moisture, the stem swells and then during droughts slowly contracts. The C. hexagonus contains cortical bundles which are vascular bundles that are remarkably like the veins of a leaf, extending in a three dimensional pattern out from the central vascular bunles. The cactus has both xylem and phloem. This tropical cactus is a flowering cactus. The blooms are slender-tubed, many stamened, and 5 to 6 inches wide. The white blooms develop freely along the stems with petals covered with a thin cuticle. The flowers of the C. hexagonus are open for only part of a single day.

Reference for Descriptive Information:

N.Y. Botanical Garden Illustrated Encyclopedia of Horticulture by T.H. Everett. http://www.esb.utexas.edu/mauseth/ResearchOnCacti/Default.htlm

Distribution and Habitat

The C. hexagonus, a tropical cactus, grows from Surinam to N. Venezuaela and Tobago. This cactus comes from the tropical coasts of Venezuela, Guyanan, Surinam, and French Guiana.

Reference for Distribution and Habitat Information:

Desert Botanical Garden Horticulture Department

 Cultural Information

  

Soil ·   C. hexagonus grows best in 'acid standard' cactus compost: moderate to high inorganic content at a pH less than 6. The soil should be more than 50% grit.

Water requirement · The C. hexagonus should be watered sparingly in the winter while requiring copious watering in the summer.    

Light ·This tropical cactus grows in full sun.
  Humidity · C. hexagonus grows best in a heated greenhouse in which a low humidity is maintianed.
  Temperature · This cactus is intolerant to frost and should be kept at a minimum temperature of 10-15 °C/50-60 °F.
  Other ·   

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Reference for Cultural Information: The New Royal Horticultural Society Dictionary of Gardening
  

  

Propagation Methods   

Cereus hexagonus can be effectively propagated by several methods, from offsets or cuttings, to seeds and grafting. Cacti that are culumnar are easily started from cuttings. A cutting is taken from a stem section using a clean, sharp knife. Two techniques are recommended for avoding fungal invasion. The first is to simply allow all fresh cuttings to sit in a warm dry place for 1-14 days before they are placed in the rooting medium; the larger the cut surface, the longer they should be allowed to dry. During this

time, the cut moist surface will form a dry callus, which is far less prone to rot. As long as the cutting is not noticeable shrivelled, it is probabley alright to leave it to dry. Newly cut stem segments may also be dipped in garden sulpher before planting to prevent the onset of soft rot. Cuttings will root in a standard well-drained cactus

mixture if provided with bright light and cool temperatures for several months. Although the cuttings may not have develped a root system, resist the temptation to keep their soil any wetter than you would a normal cactus plant. The wetter the soil, the more likely the cuttings will rot.

Propagation of C. hexagonus by seed is an inexpensive but slow method of propagation. The ripe seed pods are simply removed. Fully mature pods should be cut open, and the seeds squashed out onto a piece of paper towel where they can dry at normal room temperature. Early spring is the best time to sow cactus seed. A small pot or shallow pan is ideal for germinating the seeds. The container should be filled nearly to the top with rich, free-draining cactus soil. After firming the growing medium, seeds can be evenly spread on top. The seeds can then be

covered by sifting a very thin layer of sand over top of them. The newly sown seeds can then be watered by sitting the pot in a shallow tray of water until the top of the growing medium has become moist.

It can be covered with a clear plastic bag and placed in a location that receives bright light, but where there is no direct sunlight. Once several weeks have passed with no new seedlings emerging, the plastic bag can be removed, and a bit more sand sifted over the seedlings to provide them with better support. The seedlings should not be introduced to full sun for at least a year.

 

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References for Propagation Methods:

http://www.extension.unr.edu/Plants/propagcht.html

Uses/ Fun Facts

  

   Treelike species of Cereus, such as C. hexagonus, are often grown for ornament in warm, dry areas.

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References for Uses and Fun Facts:

New York Botanical Garden Illustrated Encyclopedia of Horticulture by R.H. Everett

 General References

  The New York Botanical Garden

Berkeley Botanical Garden

http://www.wisc.edu/botit/422/GreenhTour2.html

http://sr9.xoom.com/sierratses/page2.html

http://www.ag.usask.ca/cofa/departments/hort/hortinfo/plants/cactus1.html

http://www.desertgardens.com/c5.html

http://www.ag.usask.ca/cofa/deparments/hort/hortinfo/plants/cactus3.html

 

 

   

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Image References:   

All photographs courtesy of Dr. Patricia Tomlinson,

Visiting Professor of Biology at Washington & Jefferson College

This page was developed by:   

Emily Nease, W&J Class of 2001   

   

Last revised on April, 28, 2001