Septemeer 4, 1895.] 



Garden and Forest. 



355 



New or Little-known Plants. 



The American White Birches. 



THE two American white-barked Birches, Betula popuh- 

 foUa and Betula papyrifera, are readily distinguished : 

 the first by the viscid resinous glands which roughen its 

 young branchlets, by its nearly triangular long-pointed 

 leaves, broad and truncate, abruptly wedge-shaped or 

 slightly obcordate at the base, dark green and lustrous, and 

 roughened, especially early in the season, by small pale 

 glands in the axils of the conspicuousreticulate veinletson 

 the upper surface, with few obscure primary veins and red 

 petioles, by its usually solitary aments of staminate flowers, 

 and short cylindrical short-stalked strobiles which are 

 nearly upright and only about three-quarters of an inch in 

 length, with puberulous scales ; the second by its slightly 

 viscid, but not gland-roughened branchlets, by its ovate 

 acuminate short-pointed leaves, usually rounded or 

 slightly cordate at the base, dull dark green and usually 

 glandless on the upper surface, with numerous promi- 

 nent primary veins and yellow petioles, by its clustered 

 aments of staminate flowers and thick drooping strobiles 

 usually an inch and a half long, wiih glabrous scales. 

 Betula populifolia is a small tree, rarely more than thirty 

 feet high, with dull chalky white bark, and is mostly con- 

 fined to the Atlantic seaboard, where it ranges from Nova 

 Scotia to Delaware, but extends through northern New 

 England and New York to the shores of Lake Ontario. 

 Betula papyrifera is usually seventy or eighty feet tall, 

 although on the north-west coast it occasionally attains a 

 height of one hundred and fifty feet, with lustrous bark 

 slightly tinged with orange ; it grows within the Arctic Circle 

 and ranges from the shores of the Atlantic to those of the 

 Pacific, and southward to Long Island, the mountains of 

 northern Pennsylvania, central Michigan and Minnesota, 

 northern Nebraska, Montana and north-western Wash- 

 ington. 



In Plymouth and Warren, New Hampshire, and in Ar- 

 lington, Massachusetts, the Messrs. Faxon have, at different 

 times, found individual trees which vary in a greater or 

 less degree from either of these two types and show, per- 

 haps, what might be expected, that these species intercross. 

 On page 356 of this issue, a branch of one of these trees 

 found this summer by Mr. Walter Faxon at Arlington, is 

 figured, as well as typical leaves of trees of the two White 

 Birches growing with it. It will be seen that the leaves of 

 this peculiar tree are nearly intermediate in shape between 

 those of the two species: like the leaves of Betula popu- 

 lifolia, they are lustrous on the upper surface, their remote 

 primary veins are rather more prominent than those of that 

 tree, the petioles are only slightly flushed with red, and they 

 are nearly glandless ; the aments of staminate flowers 

 are in pairs, and the strobiles, although rather smaller, resem- 

 ble in shape and general appearance those of Betula papy- 

 rifera, while the scales are pubescent. 



Betula papyrifera, as is natural with a species of such 

 wide range, shovrs a greater tendency to variation than the 

 other American Birches, and it is as possible that these 

 peculiar trees represent one of its extreme forms as that 

 they are natural hybrids. Their extreme rarity, however, 

 and the fact that they are only found growing with indi- 

 viduals of the two species, certainly suggest hybrid origin 

 — a view which is strengthened by the fact that other hybrids 

 in this genus are known (see Garden and Forest, viii., 243). 



c. s. s. 



Plant Notes. 



TiLiA Americana. — Our native Basswoods have been less 

 frequently planted than some of the species of west- 

 ern Europe, and yet they are most desirable trees for 

 streets and parks. In good soil they grow rapidly and 

 attain large size ; their foliage is abundant and rich, deep 

 green in color; their flowers are delightfully fragrant, and 

 much sought by bees, and they suffer less from insects 



than the foreign kinds. A Washington correspondent 

 writes that the trying weather of the past summer has also 

 demonstrated the superiority of Tilia Americana over the 

 European species for street shade-trees. While all have suf- 

 fered more or less from the drought, the European species 

 lost many of their leaves before the weather began to tell 

 on the native one. Besides this, it was scarcely touched by 

 caterpillars in that city, while the others have suffered very 

 considerably. The southern species, T. heterophylla, is 

 rather smaller, a graceful tree with a pyramidal head, with 

 larger flowers than those of T. Americana, while its leaves, 

 which are silvery white beneath, give it a singular beauty. 

 It is perfectly hardy here. 



Hibiscus Syriacus. — The Althaea, or, as it is often called 

 in Ihigland, the Shrubby Mallow, is an inhabitant of every 

 old garden in the country, and owing to its formal appear- 

 ance and the rather unpleasing blue-red color of the flowers 

 of many varieties it is now somewhat despisecl. This is 

 one of the plants which every one has learned how to 

 prune in order to secure abundant flowers. These are pro- 

 duced late in the summer on the wood of the year, and, 

 therefore, when the shrub is cut back hard in autumn or 

 early spring it makes every effort to recover the loss by 

 sending out a great number of new shoots which all bear 

 flowers. After the plant has been pollarded for many years, 

 and the root and trunk are strong, its appearance at this 

 season is that of a bundle of long wands growing thickly 

 from a stubby stem and covered with flowers. Of course, 

 this treatment is proper if nothing but flowers are wanted, 

 but if a judicious system of pruning is begun when the 

 Altheea is young — that is, if the branches are simply thinned 

 out and cut back moderately every year— it will develop into 

 a broad round-headed small tree and make a' very attrac- 

 tive specimen. The flowers of the different garden forms 

 vary widely in color, and some of them are really beauti- 

 ful, although, unfortunately, they have no fragrance. It is 

 the best of shrubs for city yards, since it endures drought 

 and dust and smoke, while fev*' insects or diseases attack 

 it, and its smooth dark foliage remains good till late in 

 autumn. 



Ananassa sativa variegata. — While the ordinary Pine- 

 apple plant is not remarkable for its beauty, this variegated 

 form takes a high rank among plants with striking foliage. 

 The leaves are two or more feet long, spreading, canalicu- 

 late, with slightly spinate edges. Their color is green in 

 the centre, edged with ivory-white and often suffused with 

 bright orange or scarlet, or shades between the two. The 

 white and scarlet in the leaves is generally clearly marked, 

 and sometimes there are only faint lines of green in the 

 centre. This variety will flower and fruit, just as the or- 

 dinary Pineapple does, at a height of about three feet. It 

 will stand plenty of rough usage, extreme heat, drought 

 and sunshine, without apparent injury. Its rosette of 

 leaves is compact and regular, and few better plants can 

 be found for a choice collection. It can be grown either in 

 hanging-baskets or pots in a compost of equal parts fibrous 

 peat, sphagnum and broken pieces of dry cow-manure. It 

 will also do well in ordinary soil, provided the pots are 

 well drained. It prefers a sunny position, and while an 

 occasional drying is not injurious, moderate moisture at 

 the roots is best. It should be sponged occasionally to 

 keep it free from dust, but it is not under ordinary con- 

 ditions subject to insect pests. Propagation by means of 

 the young growth above the fruit is slow, but easy. Strong- 

 growing plants can be topped to induce them to form 

 several new growths, which in their turn may be taken ofif, 

 potted in fibrous [5eat in small pots, and placed in bottom- 

 heat, where they soon root. This is the best way of 

 propagation. Ordinary summer heat is sufficient during 

 all stages of growth, but a somewhat higher temperature 

 • facilitates propagation. 



Aristolochia elegans. — This climber is well known to 

 cultivators of greenhouse plants, and when ample root- 

 room is provided it usually grows very thriftily. It has 

 abundant twining stems and neat small, very slightly ^lau- 



