368 THE FLORAL WORLD AND GARDEN GUIDE. 



Many doubts still exist as to the species of Cereus, as they vary 

 so much both in their habit and spine and angular formation, and 

 the situations in which the}^ are found do not seem to make any 

 exception in this respect. A recent traveller and collector informed 

 me that he found from four to six different forms on the same stem, 

 so different that even the greatest connoisseur would have supposed 

 each separate branch to have been another species ; and his speci- 

 mens confirmed the assertion. 



The genus Cereus, with the exception of some species, flowers 

 more sparingly than those of Mammillaria and Echinocactus ; but, 

 from an improved method of cultivation in modern times, many 

 species have been brought into flower that were formerly not ex- 

 pected. Most of the species may be cultivated in the open air, in a 

 protected sunny situation, in summer, and it is better if they can be 

 on beds that have a little bottom-heat at first ; and this can easily be 

 eff'ected in gardens where there is plenty of leaves and manure, as 

 pits can be dug, and these materials put in and then covered with 

 earth, and the plants sunk into it. They grow extremely well in 

 this manner, are much stronger, and look a great deal better than 

 when they are continually standing in a hot-house. Several species 

 of ]y!exican Cereus can be kept through the winter in a moderately- 

 heated greenhouse. Those alluded to are such as G. chilensis, cine- 

 rasceiis, pentalophus, ovatus, '^ articulatus , Martianus, flagriformis^ 

 Mallisoni^ Smithii, iichranhii coccineuSj Ackermanni, etc., with all 

 the varieties of C. speciosissimus, etc. 



Our knowledge of the numerous group of the flat-branched 

 OpunticB is much too limited at present to enable us to determine 

 the species, but we hope in time to establish a system, and particu- 

 larly for those gardens where this tribe of plants is cultivated. 

 What a difi'erence between an Opuntia which has been grown in the 

 open air in summer, and one which has been kept in a hot-house ! 

 The difference is indeed so great, that it is hardly to be believed. 

 The most effectual manner of cultivating them in winter is, to take 

 great care not to keep them too warm, and to see that their growth 

 may not be accelerated, as a stagnation in vegetation should, if 

 possible, be eftected in the plants. As soon as the weather is 

 favourable in spring, and strong frosts no longer dreaded, they 

 should be set out in the open air, in a warm, protected situation, 

 and treated in every respect as much as possible like the genus 

 Cereus. Bottom-heat, however, is not necessary for them in the 

 open air, as they thrive better without it, the different species 

 assuming a more distinct character, and having a greater profusion 

 of flowers. How very different, also, are the O. glomercdce, grown in 

 the open air in summer, and in the cold greenhouse in winter, to 

 those that have been continually in a stove, the temperature of 

 which is not natural to them. The same may be said of O. cylin- 

 dracea, and particularly 0. tunica^ excuviata, imbricaia, Stapelia, and 

 decipiens. The first mentioned never has a stem in its native country 

 or in our cold greenhouses, but has, on the contrary, a full branch- 

 less cosspesj in the form of a hedgehog. This appearance is not- 

 uncommon, even on specimens from their native country, but their 



