10 



THE AMERICAN BOTANIST 



fact, many species become quite dormant at this season and the 

 temperature makes no difference to them. 



The way to succeed with most irises is to plant them in 

 good garden soil in a sunny situation and then let them alone. 

 During the growing season they need as much water as other 

 plants, but not more. They may be given a light mulch in 

 winter though most species appear to get along all right 

 without this. One section of the family, however, requires 

 more care. This is the so-called Oncocyclus or cushion iris 

 section whose members came originally from a region so hot 

 and dry that they die down to the ground after flowering. 

 With us, instead of having to be given water, they actually have 

 to be protected from; it for part of the year, either by means 

 of hot-bed sashes placed over them or by being dug up and 

 placed under shelter; otherwise they would start into growth 

 at the wrong time. These plants require considerable lime in 

 the soil to do well; in fact nearly all irises are fond of lime. 

 The Japanese iris (Iris laevigata) is one of the few that are 

 supposed to dislike lime, and its cultivation is not always 

 attended with success, but it is one of the handsomest of the 

 family and its beauty makes it worth much care. 



Not only do the irises thrive in gardens, but those most 

 often cultivated are so well suited to such conditions that they 

 multiply very rapidly. They really ought to be dug up every 

 three or four years and thinned out. All the irises grow from 

 underground stems which are either rhizomes or corms. The 

 rhizomes are thickened root-like parts extending horizontally 

 at or just beneath the surface of the earth from which the real 

 roots grow. The corms, usually miscalled bulbs, are erect and 

 somewhat deeper in the soil. The species with rhizomes mul- 

 tiply most rapidly. The main axis branches again and again 

 and each branch with its quota of roots will form a new plant. 

 If one wnshes to multiply his specimens he has only to tear the 

 plants to pieces and replant the separate parts. 



