376 THE NURSERY-MANUAL 







Ornithogalum (Star of Bethlehem). Liliaccce. 



Commonly increased by bulbels or offsets, and by division ; also 

 by seeds when they can be had. 



Orobus : Lathyrus. 



Orontium. Aracece. 



Increased by division, but seeds may be used if there is less 

 haste. See Aracece, page 239. 



Osmanthus (Japan Holly). Oleaceae. 



Propagated by cuttings of half -ripened wood in late summer 

 under glass, or by grafting on osmanthus stock, or on privet. Seeds 

 are rarely obtainable and do not germinate until the second year. 



Osmaronia, Nuttalia. Rosacece. 



Propagated by seeds, stratified or sown as soon as ripe ; by 

 divisions ; by suckers from the roots. 



Osmunda (Flowering Fern). Osmundacece. 

 Mostly by division; sometimes by spores. See Ferns, page 312. 



Ostrowskia (Giant Bell wort). Campanulacece. 



Propagated by root- or top-cuttings in spring. Seeds, unless sown 

 fresh, require a long time for germination and seedlings may not 

 mature under three or four years. 



Ostrya (Hop Hornbeam). Betulaceas. 



Usually grown from seeds sown when ripe or stratified. Also 

 increased by layering ; or it can be grafted. The European species 

 is often grafted on the hornbeam (carpinus). 



Othonna. Composites. 



Propagated by pieces of the stem, treated as cuttings, or taken 

 off after rooting if plant lies on ground. 



Ouvirandra : Aponogeton. 



Oxalis. Oxalidacece. 



Propagated by seeds, division and cuttings ; the tuberiferous 

 species are increased by the underground tubers. 



Oxydendrum (Sorrel-Tree). Ericacece. 



Increased by seeds, handled as for andromeda and similar things ; 

 also by layers, which often root with difficulty. 



