May 2, 1888.] 



Garden and Forest. 



II 



/ 



Notes from the Arnold Arboretum. 



THE Arnold Arlioretum is a Museum of woody plants, — a 

 great garden in whicli are being introduced, studied and 

 arranged hardy trees and slirubs from all parts of the world ; 

 and which is to be equipped with a dendrological inuseum, a 

 herbarium and a library. 



The establishment is not old, but its nurseries already con- 

 tain a very large collection of plants ; and its influence, gained 

 through the publications of its officers, and by its distribution 

 of new or little known plants, is already considerable; and there 

 is hardly an important collection of plants, in the United States 

 or in Europe, which has not been enriched by contributions 

 from the Arnold Arboretum. Its local intiuence is very con- 

 siderable, and the gardens and grounds in and about Boston 

 give aijundant proof of the interest awakened in arboriculture 

 and of the practical advantage which a community can derive 

 from a public establishment of this character. 



The final planting of the tvpe-coUection of trees in the Arbo- 

 retum has been considerably delayed by extensive and ela- 

 borate road-making, although the typical species of the most 

 important genera, like the Pines, Larches, Spruces, Firs, Chest- 

 nuts, Oaks, Walnuts, Hickories, Beeches, Birches, Elms, Ashes, 

 etc., are now permanently arranged and planted. The collec- 

 tion of hardy shrubs is extensive and important, containing 

 about twelve hundred species and well marked varieties, 

 among which there are very few garden hybrids or varieties. 

 This collection is arranged in thirty-seven parallel beds each 

 ten feet wide and two hundred and twenty-five feet long. The 

 genera are arranged in the order adopted by Bentham and 

 Hooker in their " Genera Plantaruin" and the species are ar- 

 ranged geographically so far as it is practicable to do so, first the 

 North American, then the European, and then the Asiatic plants. 

 The collection is particularly rich in North American shrubs, 

 many of which have been here first introduced into cultivation, 

 and it contains many Chinese and Japanese plants, which, if 

 from northern latitudes, generally do well here. INIany genera 

 are well represented ; of Rosa, for example, there are about 

 sixty species and many natural varieties, of Berberis thirty spe- 

 cies or more, with some varieties, and of many others a pro- 

 portionally large number of species. 



The proper determination and labelling of the plants in the 

 collection is a serious and difficult labor. Large numbers of 

 plants are sent to the Arboretum every year from other 

 botanical establishments or nurseries. iVIany of these plants 

 are incorrectly named, and very often the same species or 

 variety comes from half a dozen different places under as 

 many names. AUadditionsas soon as they bloom are verified 

 or determined, and specimens prepared for the herbarium. 

 After their identity has been settled, duplicates are removed ; 

 and the collection as it now stands is fairly well classified. 

 Numerous additions, however, are still to be made. 



It is proposed to publish in Garden and Forest, front week 

 to week during the coming season, notes concerningsuch new, 

 little known, or specially desirable plants in the collections of 

 the Arboretum as may appear worthy of record. 

 Arnold Arboretum. J , G, yack. 



The Forest. 



The Forest Vegetation of Northern Mexico. — III. 



Prosopis julifiora, DC, Mesquit. — No tree carrying 

 tiirough the entire summer so much foliage has greater 

 power to endure arid conditions than the Mesquit. 

 (See illustration, p. 116.) Its leaflets, though numerous, 

 are small, and are w^rapped in a thick and close 

 epidermis, which prevents rapid loss of their mois- 

 ture. Hence it is to be found on the most arid tracts 

 of sand and driest mesas of the plateau region. It is 

 strictly a denizen of plains and valleys, never being seen 

 amongst the growths of hills and mountains. Whilst in 

 the rich and deep soil of the bottoms of valleys of less 

 elevation, as those of Sonora notably, it grows to the 

 stature of a large tree of great value, and forms the heaviest 

 forests of such districts, in the drier situations mentioned, 

 in order to adapt itself to the conditions of its environment, 

 it takes the form of a shrub, vi^idely branching beneath the 

 soil, and rising from two to ten feet only above it. If 

 standing amongst drifting sands, these gather in hillocks 

 amidst such broad clumps of bushes, and heap themselves 



higher year by year, as the branches push upward for light 

 and air, until the amount of wood which forms under- 

 ground in thickened branches and roots is surprisingh- 

 large. A similar accumulation of wood in the roots take's 

 place when the Mesquit stands in the more stable soil of 

 mesas and grassy plains, and its branches are occasionally 

 cut away for firewood. It is the gathering of these sub- 

 terranean stores of fuel that has given rise to the saying 

 that in these regions men have to dig for their wood. 



Within the State of Chihuahua it is in a few valleys only, 

 and there growing scattered, that the Mesquit deserves 

 the name of small tree. On the deeper bottom-lands of 

 the Laguna country, through which runs the boundary be- 

 tween the States of Coahuila and Durango, it attains a 

 trunk diameter of eight or ten inches, forms dense growths, 

 and is exclusively cut for railroad ties. In the fertile val- 

 leys and more humid climate to the south and east of the 

 State of Zacatetas it is a common tree, and is encouraged 

 to grow in grain fields even, where its falling pods, in shape 

 and size resembling those of the white field Bean, pulp)^, 

 sweet and nutritious, are harvested with care as food for 

 man and beast. On account of its fruit the Mesquit pos- 

 sesses great value in the more desert districts. The pods 

 begin to mature before the midsummer rains start the 

 grass, and the half-famished herds are attracted to the 

 bushes by the rich morsels they offer. 



Growing with the shrubby Mesquit of the plains and 

 valleys, itself armed at the nodes of its twigs with straight, 

 sharp thorns an inch or more in length, are several other 

 ligneous species of low stature nearly all abundantly fur- 

 nished with thorns or hooked spines, so that passage 

 through such growths either on foot or in the saddle is dif- 

 ficult and vexatious. Of most frequent occurrence, per- 

 haps, certainly one of the most hateful, is Celtis pallida, Turr., 

 which grows in broad clumps six to ten feet high, and 

 forms, with its numerous and dense, often intricately tan- 

 gled branches, impenetrable thickets. Hardly more dread- 

 ful than this or less common is lilitnnsa biuncifera, Bcuth., 

 standing three to six feet high in widely branching clumps, 

 and laying hold of one passing it with a hundred sharp and 

 strong hooks. Acacia Greggii, Gray, the Cat's-claw Mes- 

 quit, here less common than the last, and but a shrub, is 

 a similar annoyance. So, too, Acacia Rxmeriana, Schlecht, 

 Microrhajnnus ericoides, Gray, one to six feet high, and 

 Co?idalia spathulata. Gray, var. , six or eight feet, have ex- 

 ceedingly small leaves, and bear a thorn at the end of 

 every branchlet, while Kivberlinia spiuosa, Zucc, is entirely 

 leafless, and its branches are nothing but an aggregation of 

 large thorns. In dry and sa-ndy soil this plant grows but a 

 foot or two high and spreads over broad patches ; in val- 

 leys of the plateau it is commonly an erect bush ; and on 

 the low plains of Sonora I have seen it reaching a stature 

 of fifteen or twenty feet, with a trunk diameter of six to 

 eight inches. A Cactus, Opunlia arhorcscens, Engebn., 

 on the plains five to ten feet high, but seen by Wislizenus 

 in the Laguna country thirty or forty, its surface covered 

 \\ith myriads of needle-like spines and minute barbed 

 points, presents, however, a climax of horrors to him who 

 falls into its widespread arms. Amidst this chaparral the 

 traveler acquires an instinctive dread of contact with any 

 bush ; and, if in the saddle, finds that his horse disobeys 

 the rein that would guide him near one. C. G. Pringlc. 



Wood from the American White Pine, taken from old trees, 

 is held by some authorities to be very durable because it is filled 

 with resin. But this theory seems Ijaseless. The heart-wood 

 of a tree which I exanfined in Wisconsin contained 6.g6 

 per cent, of solid resin in 100 parts, by weight, of absolutely 

 dried wood substance. A Bavarian tree examined for com- 

 parison contained 6.66 per cent. The hot weather of America 

 during the summer season may account for the small dif- 

 ference. 



It is a well known fact that the wood of trees with very little 

 resin, like the different species of yuiiiperus, Seqtioia, Ciipressiis 

 and Taxodium, is hardly surpassed in durability by that of any 

 Pine-tree, which contains the highest amount of resin. 



