Category Archives: Cacti and Succulents

Colonization of volcanic lava Flow

One of the most destructive natural disasters is the volcanic eruption, the red hot lava destroys all it comes into contact with, no living thing in its path will survive. Yet volcanic islands can have some of the richest and most diverse floras in the ivorld and in Italy some of the richest farm land is on the slopes of Mount Vesuvius. Hawaii is hundreds of miles from the nearest land, and yet this volcanic island has a very rich and varied flora.

By studying the plant colonization of volcanic lava here it was seen that no decomposition of the rock to form soil is necessary before plant growth becomes possible. As it cools the lava forms a hard porous rock which is rich in various minerals, especially phosphorus, and is capable of holding sufficient water to allow plant growth. On Hawaii, Koua, one of the largest forests, grows on a minimum of soil on relatively uudecomposed lava flows.

Hawaii is so far from the nearest land that it is highly unlikely that even those seeds adapted for wind dispersal were carried this far by the wind. Most seeds were probably brought here originally by birds, but all species will have arrived through necessity by long distance dispersal. In fact as many as 50 species are known to have come from North America.

Colonization of volcanic lava Flow
Some of the first species to have arrived will have been those with small fleshy fruits, such as Vaccinium, which are popular with birds. The birds eat the fruit before migration and deposit the seed in their excretion on the lava. Other early colonizers would have been ferns, their small light spores easily catching in the mud on the birds’ feathers and feet.

Seeds may arrive by various methods. The largest single-seed fruits, such as the coconut, are capable oj floating in sea water for some considerable time before they may be washed up on an island’s shore. Other seeds may float on rafts or drift wood.
Such a fertile substrate as a lava flow will not long he without vegetation wherever it is situated. Even in the very arid Galapagos Islands a few plants grow on pure lava, including the endemic cactus, Brachycereus nesioticus.

The Saguaro desert community

Biggest of all cacti, the Saguaro, Carnegeia gigantea, sometimes reaches 15m (45ft) in height. Older specimens usually have several side branches, sometimes bent into extraordinary curves. Seedlings grow very slowly and large plants only put on about 4 inches a year. The biggest are over 150 years old. This huge structure has, like most cacti,Continue Reading

Best Cacti and other Succulents to grow indoors

Plants which can be grown in the home are so varied now that there is no corner of it that will not suit some plant completely. Although there are many indoor plants which will not be happy in the extremely hot and sunny conditions of a south-facing window, there are a few exceptions such asContinue Reading

PORTULACACEAE

In this family two genera are found which interest the collector of succulent plants. They are the genus Anacampseros and the genus Portulacaria. ANACAMPSEROS. The genus is native to S. Africa. In practically all the species the flowers are rather small. The seed ripens quickly and is dispersed immediately. The genus is divided into fourContinue Reading

Succulent Care Through the Year

January/February Epiphyllums, Zygocacti, Rhipsalis and climbing cacti, the leafy Euphorbias, Crassulas, Echeverias, and Conophytums may be given a very light watering with lukewarm water once or twice during the month if the weather is really fine and sunny. Ventilate on sunny days and lightly spray your collection of plants, but it is essential that allContinue Reading

COMPOSITAE

Although this is a very large family of plants, only 3 genera are of interest to growers of succulents. They are Kleinia, Othonna, and Senecio. All require plenty of light and fresh air and during winter a very sparing supply of water, for most species are at rest and moisture at this time of yearContinue Reading

OTHONNA

The genus consists of about 11 species, native to S. Africa, but only one of these is normally cultivated. Othonna crassifolia. A useful hanging plant with fleshy leaves of a fresh green colour and bright yellow daisy-like flowers which are produced almost throughout the whole year. The plant is easy to grow, requiring a richContinue Reading

SENECIO

Closely allied to the genus Kleinia and native to Cape Province. Senecio scaposus. Has round fleshy leaves, pencil-shaped, 4 inches long; on the upper surface of the leaves, and just below the tip, a small flattened area occurs. The young leaves are enveloped in a silvery felt-like skin which later breaks open and allows theContinue Reading

BROMELIACEAE

There are many Bromeliads, which grow in very exposed dry places, that have developed tough, leathery leaves, and among them are the Dyckias which are popular with collectors. DYCKIA. They are mostly natives of Brazil, but a few are to be found in other parts of S. America. Generally speaking, the Dyckias are not difficultContinue Reading

EUPHORBIACEAE

This very extensive family of plants contains a large number of annual and perennial herbs and woody plants of the ordinary herbaceous type, as well as many plants which are succulents. The most interesting of these are in the genus Euphorbia. EUPHORBIA. These are natives chiefly of S. Africa, where they grow in the desertsContinue Reading