130 



THE FRUIT. 



20. 



thin scales which fall off at the touch ; in the Sneezewe^d, of about 

 five very thin scales, which look more like a calyx (Fig. 294) ; and 

 in the Thistle, Aster, Sow-Thistle (Fig. 295), and hundreds of others, 

 it is put up into a tuft of fine bristles or hairs. This is called the 

 Pappus ; a name which properly means the down like that of the 

 Thistle ; but it is applied to all these forms, 

 and to every other under which the limb of the 

 calyx of the " compound flowers " appears. In 

 Lettuce, Dandelion (Fig. 296), and the like, ' 

 the achenium as it matures tapers upwards 

 into a slender beak, like a stalk to the pappus. 



350. A Utricle is the same as an achenium, but with a thin and 

 bladdery loose pericarp ; like that of the Goosefoot or Pigweed 

 (Fig. 297). When ripe it bursts open irregularly to 

 discharge the seed ; or sometimes it opens by a circular 

 line all round, the upper part falling off like a lid ; as in 

 the Amaranth (Fig. 298). 



351. A Caryopsis, OF Grain, differs from the last only 

 in the seed adhering to the thin pericarp 

 throughout, so that fruit and seed are in- 

 corporated into one body; as in wheat, In- 

 dian corn, and other kinds of grain. 



352. A Nut is a dry and indehiscent fruit, 

 commonly one-celled and one-seed*; 1, with a hard, crus- 

 taceous, or bony wall, such as tne cocoanut, hazelnut, 

 chestnut, and the acorn (Fig. 21, 299). Here the 

 involucre, in the form of a cup at the base, is called the Cupule. 

 the Chestnut it forms the bur ; in the Hazel, a leafy husk. 



FIG. 291. Acheninm of Mayweed (no pappus). 292. That of Succory (its pappus a shal 

 tow cup). 293. Of Sunflower (pappus of two deciduous scales). 294. Of Sneezeweed (Hele- 

 nium), with its pappus of five scales. 295. Of Sow-Thistle, with its pappus of delicate downy 

 hairs. 296. Of the Dandelion, its pappus raised on a long beak. 



IG. 297. Utricle of the common Pigweed (Chenopodium album). 



FIG. 298. Utricle (pyxis) of Amaranth, opening all round (circumciBBil*,. 



FIG. 299. Nut (acorn) of the Oak, with its cup (or cupule). 



