4i8 



turned yellow, shi\elled up and dried into a mass which finally crumbled. 

 The injury is horticulturally of significance only when the blooms are forced 

 and large individual blossoms are desired as in Lilium aureum. Lilium longi- 

 florum and Hippeastrum robustum, Dietr., etc. 



In that species which is known among gardners as Amaryllis Tettaui 

 and is often grown as a house plant because it blooms freely, I observed 

 more carefully the mechanics of opening and incomplete development dur- 

 ing drought. 



The three outer tips of die brick red perianth begin to separate from 

 one another at their base on the day before the blossoms are completely 

 opened; hence the large conical flower bud first of all shows three slits. 



The tips of these three outer- 

 most petals, however, remain 

 stuck fast together even if 

 the process of separation from 

 one another is so hastened by 

 the increased growth of the 

 innerside of the perianth that 

 this is curved outward like a 

 pouch. In this convexity, 

 which becomes constantly 

 greater, lies a great elasticity 

 which would be able to sep- 

 arate the gummed tips from 

 one another and, in normal 

 cases, actually does tear them 

 apart. The strength of this 

 elastic power, produced by 

 the basal epinasty of the 

 perianth, is demonstrated if 

 the still gummed apices of the 

 three tips are cut off about 

 forty-eight hours before the 

 normal time of opening. Then, within lo minutes, the individual tips have 

 separated 1.5 to 2 cm. from one another, i. e. the corolla has begun to open. 

 The resistance offered to this strong elasticity arises from the fact that the 

 green apices of the three outermost tips are anchored to a strong cone about 

 5 cm. long. Sometimes this cone is thimble shaped. There is a heavy 

 growth on the underside of each tip which curves out like a ridge, and 

 corresponds with a midrib, making a very fleshy growth on each tip. 



Fig. 69 shows three of the perianth tips, touching each other with their 

 keel-like wedges (a). These wedges contain no vascular bundles. These 

 lie {§) frequently in groups of 3 or 4 peripherally in the real laminal part. 

 The individual laminal halves at both sides of the fleshy median ridges are 

 curved inward and touch the adjacent peripheral tip with their edges (r) ; 



Fig. 69. Cross- section through the apical region 



of a still closed blossom of Hippeastrum 



robustum. Explanation of the letters 



in the text. 



