June 21, 1893.] 



Garden and Forest. 



265 



The production of hybrids between Azaleas and Rhodo- 

 dendrons is not new. In 1837, Dean Herbert, in his his- 

 tory of the Amaryllis family, describes on page 356 a 

 Rhododendron azaleoides obtained by the accidental fer- 

 tilization of an Azalea by the pollen of Rhododendron Ponti- 

 cum. According to our contemporary, a cross raised by 

 Mr. Smith, a nurseryman of Norbiton, from Rhododendron 

 Ponticum, fertilized with the pollen of Azalea Sinensis, was 

 exhibited at Ghent as long ago as 1839. Seedlings of this 

 cross were once well known in England as the Norbiton 

 Hybrids, and one of them was figured in Paxtotis Maga- 

 zine of Botany in 1842. This was an evergreen shrub with 

 wrinkled leaves and with large clusters of terminal flowers 

 shaded and spotted with light brown. From time to time 

 other hybrids have appeared in European gardens raised 

 by crossing Rhododendrons and Azaleas. Such hybrids, 

 apart from their ornamental value, which is likely to be 

 considerable if a race of hardy evergreen yellow-flowered 

 Rhododendrons can be obtained, are interesting as show- 

 ing that the view of modern systematic botanists who unite 

 Azalea and Rhododendron in one genus is the correct one. 



Cultural Department. 



Caraganas or Siberian Pea-trees. 



THIS group of shrubs, belonging to the Leguminosas or Pea 

 family, possesses a good deal of interest to every one 

 who cultivates woody plants. The several species in cul- 

 tivation are so varied in form and habit tliat they present very 

 different aspects, and, to the casual observer, do not always 

 show their close relationships. Most of those known are per- 

 fectly hardy in this latitude, and will endure the winters with- 

 out injury in localities where the cold is much greater. Indeed, 

 they should be hardy, for they are largely natives of Russia 

 and Siberia, the hardy species extending southward through 

 such countries as Turkestan and to the mountains which form 

 the northern boundaries of India. All have small pinnate 

 leaves, and the characteristic color of the flowers is yellow, or 

 in some species more or less reddish. Ahhough some of 

 them have been long in cultivation in the Old World, they are 

 comparatively rare in American gardens. All are very easily 

 propagated by seeds or grafts, and are also sometimes in- 

 creased by layers or root-cuttings. They will grow in almost 

 any garden soil and will thrive in many poor sandy tracts. 



The largest, most robust, and in many respects the most de- 

 sirable species is Caragana arborescens. This will bloom well 

 when only two or three feet high, but with room to develop it 

 will assume a small tree-like form and attain a height from ten 

 to twenty feet. Sometimes several of its smooth-barked, red- 

 dish brown stems grow from the base instead of a single trunk. 

 There are usually six or seven pair of small, oval or obovate, 

 mucronate, light green leaflets to each leaf on the strong new 

 growths, but fewer leaflets on the flowering branches. The 

 bright yellow Laburnum-like blossoms are produced in abun- 

 dance on individual short stalks, and in this latitude they 

 usually begin to open about the middle of May. While they 

 suggest Laburnum-blossoms, they lack the showiness and 

 grace of those flowers, which are aggregated on long leafless 

 racemes. This Caragana, however, is quite out of bloom be- 

 fore Laburnum-blossoms appear, and as yellow-flowering 

 shrubs at this season are not common, it has a peculiar value. 

 Moreover, it will grow in climates and situations too severe 

 for the Laburnum, which is not such a strong and enduring 

 plant. The small fruits, resembling pea-pods, mature about 

 the middle of July. Soon afterward, on dry warm days, the 

 pods open with a sharp audible snap, and the seeds are often 

 scattered for many feet around. With slight encouragement 

 they soon germinate and form young plants the same season. 

 There is a weeping or pendulous form of this species, which 

 is odd-looking when grafted on a tall stem. 



We have growing in the Arboretum several so-called varie- 

 ties of C. arborescens, but they are probably forms of another 

 species known as Caragana Altagana. This is a smaller, more 

 slender shrub, with more numerous but much smaller leaflets, 

 usually not over a quarter of an inch in length, and it is fur- 

 ther characterized by producing its flowers mostly singly from 

 each group of buds instead of a number of flowers in a sort 

 of cluster, as in C. arborescens. It is not such a showy, and, 

 therefore, not such a desirable shrub for general cultivation. 

 It blossoms later than C. arborescens, however, and has a 

 value in keeping up the succession of bloom. Among the 



plants which seem more nearly allied to this are specimens 

 received under the names of the Sand Caragana, or C arbo- 

 rescens arenaria and C. microphylla. 



Caragana frutescens is a distinct species of slender habit, and 

 having two pair of small obovate wedge-shaped leaflets 

 crowded at the apex of each short leaf-stalk. Usually one, and 

 not more than two, flowers are produced from each bud. 

 They are small, little over half an inch long, of a deep yellow 

 color, and with the terminal end of the standard resupinate, or 

 well turned up and backward. As it grows here it does not 

 appear to be such a profuse bloomer as C. arborescens. It is 

 a much smaller and more slender plant, with darker green 

 foliage, which better sets off its blossoms. 



Caragana grandiflora seems to be a distinct species, having 

 four large dark green leaflets at the tip of each leaf-stalk and 

 with much larger flowers and stronger habit than C. frutescens. 

 If the blossoms were produced in greater abundance it would 

 be the handsomest of all the species which are hardy here. 

 So far the solitary pediceled flowers seem somewhat scattered 

 as they appear in this vicinity. 



Caragana Chamlagu, a Chinese species, having large flow- 

 ers, fully an inch long, of a yellow color, changing to reddish 

 after full expansion, is an interesting plant, although it has not 

 proved so vigorous or hardy here as most others. Its leaves 

 are composed of four large shiny leaflets on spiny-pointed 

 leaf-stalks. The branches assume a drooping habit as they 

 grow old. 



Another drooping and very slender-branched species is C. 

 pygmaea, which is sometimes grafted on tall stems of C. arbo- 

 rescens for the drooping effect. On its own roots it is not 

 likely to grow more than two or three feet high. Its leaflets 

 are linear-obovate in shape and crowded in fours at the base 

 of very sliort spiny-tipped petioles. The very small foliage 

 allows full exposure for the bright yellow flowers, which are 

 of good size but not very abundant. It blossoms in the season 

 of the Laburnum. 



It is characteristic of Caraganas that they bear a pair of more 

 or less developed spiny stipules at the base of each leaf-stalk, 

 and the tip of each leaf-stalk or rhacis ends in a sharp spine. In 

 some species these leaf-stalks fall with the leaflets, but in others 

 they persist for a year or more longer and give the plants 

 quite a formidable appearance. They persist on C. frutescens, 

 but are not conspicuous, and they also remain on C. Cham- 

 lagu. On C. spinosa, however, they are from an inch to an 

 inch and a half long, slender and needle-like, fairly woody and 

 rigid, and capable of inflicting ugly pricks and deterring small 

 animals from passing among them. The branches of C. 

 spinosa are long and numerous, and interwoven they form an 

 impenetrable low hedge. The plant will grow four or fivefeet 

 high under cultivation. Its small leaves and buds are covered 

 with short soft gray pubescence, which gives the whole plant 

 a hoary or grayish aspect. The flowers are large, yellow 

 and solitary. While it does not appear to be a profuse bloomer, 

 the plant is worth cultivating, on account of its curious appear- 

 ance, in every garden where vegetable oddities are desired ; 

 and there are many situations where its value as a low hedge 

 would seem obvious. It is likely to grow on dry or sandy 

 soils where some other hedge-plants would be a failure. 



Arnold Arboretum. J • G. jfaCK. 



Some California Raisin Grapes. 



T EADING California growers are experimenting with seed- 

 ■*— ' ling Raisin Grapes, and, although they vary greatly, some 

 seedlings of promise are already beginning to bear. A larger 

 seedless Grape is desirable and is quite likely to be obtained. 

 There are now two types of the Muscat Grape grown for 

 raisins in California. The type preferred in southern Califor- 

 nia is the true Muscat of Alexandria ; this is the variety 

 most esteemed for this purpose in \^alencia and Smyrna. The 

 large, firm berry is egg-shaped, smaller at the stem-end, and 

 when cured and packed this Muscat looks a little smaller than 

 Muscatels of the same grade. The Muscatel, or Gordo bianco 

 Grape, while similar in general appearance to the Muscat of 

 Alexandria, is distinct in habit of growth, style of cluster and 

 form of fruit. The vine spreads, but more evenly, without 

 the upright cane so often seen in the Muscat ; the clusters are 

 more compact and the berry is rounder, being a short oval. 

 This is more nearly the type of the best raisin grapes of the 

 Malaga district, and is the favorite raisin grape of the San Joa- 

 quin valley. A third type of the Muscat class, though not yet 

 grown to any extent, is the Huasco, of Chili. This is said to 

 be a seedling of the Muscat of Alexandria, and produces, in 

 its native country, a very fine and high-priced raisin. As tried 

 in California it does not maintain its local reputation. Vines 

 have been sent to distinguished ampelographers of Europe, 



