C. triangularis (three-angled); Bot.  Mag. 1884.—­This plant is easily recognised because of its stout triangular stems, which increase at a rapid rate and bear roots freely; by means of these roots they cling to almost any substance with which they come in contact.  There are large examples of it in the Kew collection, where it bears numerous flowers annually, which open in the evening and close at about eight o’clock next morning.  The flowers measure 1 ft. in length by about the same in width of cup, and are composed of a whorl of long narrow green sepals, with pale brown points, a cluster of pure white petals, bright yellow stamens, and a large club-like stigma; they appear in autumn.  Mexico.  This species was cultivated at Hampton Court in 1690.

C. speciosissimus (most beautiful).—­Although not a night-flowering kind, nor yet a climber, yet this species resembles in habit the above rather than the columnar-stemmed ones.  It is certainly the species best adapted for cultivation in small greenhouses or in the windows of dwelling-houses, as it grows quickly, remains healthy under ordinary treatment, is dwarf in habit, and flowers freely—­characters which, along with the vivid colours and large size of the blossoms, render it of exceptional value as a garden plant.  Its stems are slender, and it may be grown satisfactorily when treated as a wall plant.  For its cultivation, the treatment advised for Phyllocactuses will be found suitable.  When well grown and flowered it surpasses in brilliancy of colours almost every other plant known.  Specimens with thirty stems each 6 ft. high, and bearing from sixty to eighty buds and flowers upon them at one time, may be grown by anyone possessing a warm greenhouse.  The stems are three to five angled, spiny, the tufts of spines set in little disks of whitish wool.  The flowers are as large as tea saucers, with tubes about 4 in. long, the colour being an intense crimson or violet, so intense and bright as to dazzle the eyes when looked at in bright sunlight.  When cut and placed in water they will last three or four days.  April and May.  Mexico, 1820.  “Numberless varieties have been raised from this Cereus, as it seeds freely and crosses readily with other species.  Many years ago, Mr. D. Beaton raised scores of seedlings from crosses between this and C. flagelliformis, and has stated that he never found a barren seedling.  Much attention was given to these plants about fifty years ago, for Sir E. Antrobus is said to have exhibited specimens with from 200 to 300 flowers each.  I have been informed that an extremely large plant of this Cereus, producing hundreds of flowers every season, is grown on the back wall of a vinery at the Grange, Barnet, the residence of Sir Charles Nicholson, Bart.” (L.  Castle).

The semi-scandent species.