ARBORICULTURE 



ARBUTUS 



383 



in most cases, by sooty mold fungus, resulting from 

 scale infestations. This can of course be remedied, but, 

 in the average case, at considerable more expense than 

 would be warranted. 



Eucalyptus corynocalyx becomes straggling and 

 unsightly with age. 



Eucalyptus globulus and, in fact, almost all species of 

 the genus, are frequently debarred by town ordinance 

 from growth within 60 or even 70 feet of a sewer, on 

 account of the remarkable length and penetrating 

 power of their roots. 



Eucalyptus robiista, a species which is exceedingly 

 handsome as a young tree, has been extensively 

 planted along roadsides and streets in the warmer parts 

 of the state. When mature, it becomes straggling 

 and exceedingly brittle, breaking up in an unsightly 

 way. 



Eucalyptus rudis. This species has a pendent habit 

 when older that often causes a severe splitting of the 

 crown. As the trees are very picturesque, they are 

 often desirable, provided reasonable attention can be 

 given to prevent this. 



Ficus macrophylla is injurious to sidewalks. 



Grevillea robusta has brittle wood and is usually much 

 broken in heavy winds, but can be used with satis- 

 faction if kept well cut back. 



Melia Azedarach var. umbraculiformis is unsatis- 

 factory in the immediate vicinity of the coast; as a 

 sidewalk tree it is exceedingly untidy when losing 

 leaves, and is also very much subject to scale insects. 



Paulownia tomentosa is sometimes objected to on 

 account of the somewhat untidy appearance of the 

 persistent seed-pods, which require no little labor if all 

 are to be removed after flowering. 



Phoenix dactylifera and P. reclinata both sucker 

 objectionably. 



Populus alba, Robinia Pteudacacia and Ulmus race- 

 mosa are ex'-oodmgly troublesome when used as side- 

 walk trees on narrow streets; their surface roots often 

 break the cement or asphalt sidewalks, and the suckers 

 come up in the midst of lawns several yards away from 

 the parent tree. 



Schinus Molle should be avoided in the citrous belt, 

 as it is found to harbor and become a nursery for scale 

 insects. As a street tree it is also unsatisfactory, becom- 

 ing too large and straggling, and requires too much 

 pruning to keep it within bounds; its large surface 

 roots often break cement and asphalt sidewalks. 



The species of Phosnix and Jubsea should be avoided 

 on account of their low, wide-spreading habit, except 

 for avenues and boulevards where there is no sidewalk 

 or where there is from 20 to 30 feet space between side- 

 walk and driveway. 



8. Trees for alkali soils. 



There are many places in those parts of the state that 

 enjoy a high temperature and low rainfall, where the 

 percentage of alkali salts in the soil is too great for the 

 cultivation of most of our ornamental trees, and where 

 it is very important that some shade-producing species 

 be grown. 



A. Tolerant of strong "black" alkali (sodium carbonate). 

 The most alkali-tolerant tree of those yet tested is 

 Kcelreuteria paniculata, a small species 15 to 30 feet high, 

 with feathery, pinnate leaves and ornamental yellow 

 blossoms. 



AA. Tolerant of medium alkali (chiefly "white" alkali). 



Acacia melanoxylon. 



Ailanthus altissinia. 



Albizzia lophantha. 



Casuarina cquisetifolia. 



Eucalyptus amygdalina var. 

 angustifolia (apparently the 

 least sensitive of the eu- 

 calyptus). 



AAA. Only fairly tolerant. 



Acer macrophyllum. Gleditsia triacanthos. 



Acer Negundo var. californicum Ulmus species. 

 Cinnamomum Camphora. Washingtonia filifera. 



AAAA. Tested and found unsuitable. 



Most of those trees of the humid regions, e.g., the 

 eastern states and northern Europe, which have been 

 tried on alkali soils, have been found to suffer and to 

 remain dwarf and stunted. This is particularly true 

 of Liriodendrpn Tulipifera, Quercus pedunculata and 

 species of Tilia. 



Since writing the above, the following additional 

 information on the alkali tolerance of ornamental trees 

 has been secured through the investigations of R. H. 

 Loughridge of the Agricultural Experiment Station at 

 Berkeley, and has been placed at our disposal. 



Total amount of salts found in the upper 4 feet of 

 soil in which the following trees were growing, expressed 

 in tons per acre: 



Tons per acre in depth of 4 feet. 

 Kcelreuteria paniculata ............................ 32 



Platanus orientalis ................................. 21 1 /% 



Eucalyptus amygdalina ............................. 20 



Eucalyptus angustifolia ............................. 20 



Washingtonia (species not stated) .................... 7 y^ 



Phoenix dactylifera ................................. 5 



Cinnamomum Camphora 



ARBOR VITAE: Thuja. 



Jos. BURTT DAVY. 

 B ' Y ' MoRRISON.f 



Eucalyptus rostrata (Fig. 360). 

 Eucalyptus sideroxlyon var. 



rosea. 



Phoenix dactylifera. 

 Platanus orientalis. 

 Populus Fremontii. 

 Quercus lobata. 

 Robinia Pseudacacia. 



ARBUTUS (ancient Latin name). Ericacese. Orna- 

 mental woody plants grown for their handsome ever- 

 green foliage and for their attractive flowers and fruits. 



Trees or shrubs with the bark of the branches and 

 younger sts. smooth, and usually red, exfoliating: Ivs. 

 alternate, petioled, serrate or entire: fls. monopetalous, 

 globular or urn-shaped, 5-toothed; stamens 10, included; 

 anthers with a pair of reflexed awns, the cells opening by 

 a terminal pore; ovary 5-, rarely 4-celled, cells with 

 many ovules: fr. a globose, many-seeded, berry-like 

 drupe with mealy flesh, mostly granulose outside. 

 Twelve species in W. N. and Cent. Amer., S. and W. 

 Eu., Asia Minor, N. Afr., and Canary Isls. 



The stems and branches are conspicuous by their 

 red smooth bark peeling off in large thin plates, the 

 evergreen foliage, rather large and usually lustrous 

 flowers, white to red, in terminal panicles followed by 

 attractive red fruits. They are of great decorative 

 value for parks and gardens in warm-temperate re- 

 gions; especially beautiful when adorned with the 

 clusters of white flowers or bright red berries. 



Arbutuses grow best in well-drained soil in some- 

 what sheltered positions not exposed to dry winds. 

 They are very handsome greenhouse shrubs, thriving well 

 in a sandy compost of peat and leaf soil or light loam. 



Propagation is by seeds sown in early spring or in 

 fall, or by cuttings from half-ripened wood in fall, 

 placed in sandy peat soil under glass; they root but 

 slowly. Increased also by budding or grafting, usually 

 veneer-grafting, if seedlings of one of the species can 

 be had for stock. Layers usually take two years to root. 



A. Panicles short, nodding: Ivs. usually serrate. 

 Unedo, Linn. STRAWBERRY TREE. From 8-15 ft.: 

 Ivs. cuneate, oblong or oblong-lanceolate, 2-3 in. long, 

 glabrous, green beneath: fls. white or red, ovate: fr. 

 scarlet, warty, %in. broad. Sept.-Dec. S. Eu.. Ireland. 

 L.B.C. 2:123. R.B. 31:36. G.C. III. 14:329. Var. 

 integerrima, Sims. Lvs. entire. B.M. 2319. Var. 

 rubra, Ait., and var. Crodmii, Hort., have red fls. Gn. 

 26, p. 506; 33, p. 320. F.S.R. 2, p. 375. Very beauti- 

 ful in autumn when the tree bears its large scarlet frs. 

 and at the same time its white or rosy fls. Roots and 

 Ivs. astringent. 



AA. Panicles erect: Ivs. usually entire. 

 Menziesii. Pursh (A. procera, Douglas). MADRONA. 

 Fig. 361. Occasionally 100 ft. high; trunk with dark 



