LECT. IX. j SOLID CONFIGURATION OF LEAVES. 491 



were formed by the two sides of the leaf being 

 compressed together, but separated near the 

 midrib, so that one part of the leaf is flat 

 and another tubular, as beautifully exemplified 

 in the genus Sarracenea, 4. The configuration 

 is four-edged (tetragona}, when there are four 

 longitudinal sides, and consequently four corners: 

 but if there be three sides only, as in Mesem- 

 bryanthemum aureum, the configuration is termed 



trigona, 4 (see page 492) ; Linnaeus uses trique- 

 trum to express an awl-shaped leaf, which has 

 three flat sides; but the term is superfluous. 

 Tongue-shaped (UngulataJ, 5, implies that the 

 leaf is thick, oblong, and blunt. This form of 

 leaf is often cartilaginous at the edges, as in 

 some of the Aloe tribe. The configuration is 

 gibbous (gibbaj, 6, when it is thick and swells 

 out, or is humped on one or both sides. Symitar- 

 shaped (acinaciformis) , 7) when one edge is 

 thick, flat, and nearly straight, and the other 

 thin, sharp, and curved like a symitar. Hatchet- 

 shaped (dpfabriformis), 8, when it resembles the 



