January i, 1896.] 



Garden and Forest. 



A plant, much larger than 0. Whipplei, was found a num- 

 ber of years ago by Dr. Schott south of the Gila River, 

 extending to Tucson. Dr. Engelmann considered this 

 plant a variety of 0. Whipplei (0. Whipplei spinosior). 

 As before stated, O. Whipplei has a very limited range, and 

 is confined to the southern portion of the Colorado plateau 

 at elevations of from 5,000 to 7,000 feet. The so-called 

 variety is confined to the low southern plains, growing 

 at elevations of from 1,500 to 3,000 feet above the sea, 

 where it is mingled with O. arborescens. After extended 

 field observations, I conclude that O. Whipplei spinosior 

 is much more closely related to O. arborescens than to the 

 more northern plant, and may more properly be considered 

 a variety of that species. 



Opuntia Whipplei is readily distinguished from related 

 species by its usually small size ; subprostrate habit of 

 growth ; numerous, erect, small, elongated branches, glis- 

 tening, white, loose spine-sheaths, and small, densely tuber- 

 culated, sweetish fruit, which does not turn yellow on 

 ripening, but late in fall withers and dries on the plants. 

 On the other hand, it is almost impossible to separate the 

 southern variety from O. arborescens. Both are large, 

 upright, loosely branched plants, with distinct trunks, fre- 

 quently ten to twelve inches in diameter. The branches 

 are horizontal or pendulous and arranged in whorls. When 

 fully ripened the fruits of both are yellow and well-filled 

 with juice. The seeds are numerous, dark-colored when 

 moist, but becoming white on drying. 



The greatest distinction seems to be in the flowers, but 

 here there is so much variation no specific distinction can 

 be drawn. The large magenta-colored flowers of Opuntia 

 arborescens usually have numerous broadly obovate petals, 

 while in the other plant the petals are fewer, much nar- 

 rower and acute at the apex. The flowers of the latter vary 

 in color from greenish yellow, as in O. Whipplei, to pink, 

 purple and magenta. It is possible to find plants showing 

 all of these variations only a few rods apart, and even flow- 

 ers on the same plant show considerable variation. 



The flowers of Opuntia arborescens appear in this lo- 

 cality during April and May, remain open for two or three 

 days, and are fertilized mostly by bees. These insects, 

 attracted to the flower, enter between the style and sta- 

 mens, passing down to the base of the style to get the 

 nectar. The numerous sensitive stamens immediately 

 bend forward toward the style, closing over the insect and 

 hiding it from view. It necessitates quite an effort on the 

 part of the insect to escape, but it finally forces its way 

 from beneath the stamens and climbs to the top of the 

 slightly elongated stigma, whence it makes its escape, 

 thoroughly dusted with the pollen from the numerous 

 stamens. In a few minutes the stamens assume their nor- 

 mal condition and the flower is ready for the reception of 

 other insects. I have frequently seen as many as three 

 honeybees enclosed in a single flower. 



The twenty to thirty pulvilli on the ovary are at first 

 armed with a number of slender spines which are decidu- 

 ous in December as the fruit begins to turn yellow. 

 Throughout the summer the tubercles on the ovary are 

 very prominent, but as the fruit ripens it increases consid- 

 erably in size, becomes much more succulent, and as a 

 result the tubercles are no longer prominent. The fully 

 matured fruit is frequently two inches long and one and a 

 half inches thick. After ripening the fruit remains on the 

 plant through the winter and sometimes through the next 

 summer. The persistency with which the ripened fruit 

 hangs to the plant gives rise to the popular idea that the 

 fruit does not mature until the second year. 



Occasionally flowers develop at the pulvilli of a matured 

 fruit, and other fruits are formed on the old one. In such 

 cases the fruit is proliferous, but of two seasons' growth. 

 Most usually the fruit is clustered at the extremity of the 

 branches of the previous year's growth, and during late 

 summer, autumn and winter the verticillate branches are 

 pendulous from its weight. 



The spines persist for several years, increasing in num- 



ber each year from the upper end of the pulvillus. The 

 trunk and large limbs are destitute of spines, but are cov- 

 ered with a dark brown rough bark in elongated ridges. 



The reticulated wood is used to some extent in the man- 

 ufacture of light furniture, fancy articles, canes, picture- 

 frames, etc. A factory was established in Salt River Valley 

 some three years ago for the purpose of manufacturing 

 articles from this wood. 



University of Arizona. /• W. Toumey '. 



Foreign Correspondence. 

 London Letter. 



Dendrobium Ccelogyne. — This is the largest-flowered of 

 the Sarcopodium section of the genus characterized by 

 short, erect pseudo-bulbs, springing at intervals of two 

 inches from a stout creeping rhizome and bearing a pair of 

 leaves, the general appearancesuggesting Bulbophyllum, or, 

 as in the species under notice, a Coelogyne. Sir Trevor 

 Lawrence exhibited a plant of it in flower last Tuesday ; 

 otherwise I have never seen it in flower since it bloomed 

 at Kew about seven years ago. I saw a group of healthy, 

 recently imported plants of it in the Clapton nurseries of 

 Messrs. H. Low & Co. a few days ago. The species was 

 described from a plant flowered by the late Mr. John T)ay 

 in 1871. It has pseudo-bulbs two inches long, elliptic- 

 oblong leathery leaves six inches long and solitary flowers 

 in which the sepals are lanceolate, the base of the two lat- 

 eral forming a broad chin ; the petals are linear and the 

 lip is large, fleshy, scoop-shaped and colored deep purple 

 on the front lobe, pale yellow with purple streaks on the 

 side lobes, the other parts of the flower being dull yellow 

 with reddish lines and blotches. In size the flower is about 

 equal to C. brunnea, but fleshier. The species is a native 

 of Moulmien. 



Dendrobium Treacherianum — This belongs to thes same 

 section as Dendrobium Ccelogyne, which it resembles in 

 habit, but the pseudo-bulbs are close together, longer 

 and angulate, the leaves shorter, and the scape bears from 

 two to ten flowers, which are two inches long with linear 

 segments, colored pale rose-purple and a rose and dark 

 crimson fleshy lip. It was introduced from Borneo in i88i 

 by Messrs. Low& Co., but is rare in cultivation, probably 

 owing to the difficulty most cultivators experience in keep- 

 ing it healthy. Sir Trevor Lawrence is, however, an ex- 

 ception in this respect, for he exhibited a plant this week 

 which bore three spikes, carrying twenty flowers, which 

 was deservedly awarded a first-class certificate and cultural 

 commendation. A figure of this species was published a 

 few years ago in The Botanical Magazine, t. 6591, from a 

 plant flowered in a hot moist stove at Kew. It was named 

 by Reichenbach in compliment to Mr. W. H. Treacher, a 

 government official at that time in Labuan. 



Phajus Mishmiensis is a handsome species, of which two 

 examples are now in flower in a warm house at Kew, one 

 of them being the plant described by Mr. Rolfe two years 

 ago as a new species under the name of Phajus roseus, 

 and erroneously stated to be from west tropical Africa {Kew 

 Bulletin, 1893, p. 6). The other was imported from Calcutta 

 this year as P. Mishmiensis, and the two are identical. 

 P. Mishmiensis is a native of Assam, Sikkim and lower 

 Burma, and has been known to botanists since Lindley's 

 time, although only lately introduced. I believe Messrs. 

 Low & Co. have some recently imported plants of it. In 

 habit it resembles P. Wallichii, but is smaller ; the scape is 

 two feet high and bears a dozen flowers, each about one 

 and a half inches across and colored rose-pink when first 

 opened, changing to buff before fading. There are a few 

 whitish spots on the lip and a ridge of white hairs down 

 the centre. It thrives under the same treatment as 1'. 

 grandifolius. 



Melastoma Malabathricum. — This is an old garden plant 

 of considerable beauty which has fallen into general neg- 

 lect, except in the Edinburgh Botanic Garden, where this 

 year it formed a pyramid twelve feet high, clothed from tup 



