BRACTS. 76 



its base, ihey take only the general term hract, as in the 

 Heart's ease and Veronica Oirrcstis. 



When they are verticillale and surround several flowers, 

 they constitute an involucre^ as in tlie UmbeUifcrcB. In 

 ComposiiaceiB the involucre assumes the appearance of a calyx^ 

 enclosinjr many flowers, but each floret has a calyx more or 

 less developed enclosing the seed and appearing on its sum- 

 mit in the tbrm of egrety scales or an elevated margin. At 

 the base of this involucre there are often bracts, not constitu- 

 ting a part of it ; these are called bractlets, and the involucre 

 is said to be hracteolatc. In the CupulifercB the involucre as- 

 sumes a more singular appearance, forming in the Oaks ihe 

 hard cup shaped organ enclosing the base of the acorn, and 

 in the Chestnut constituting what is well known by the name 

 of BUR. The real calyx in these cases exists in a rudimenta- 

 ry torm immediately surrounding the pistils, as may be read- 

 ily observed in the pistillate flower of the chestnut. In the 

 Cornus or Dogwood the involucre consists of the four large, 

 white, showy leaves which one, not a Botanist, would take for 

 the corolla. In the Euphorbia the involucre is composed of 

 two rows of united leaves, forming what might be easily mis- 

 taken for a calyx and corolla, as the outer part is green, while 

 the inner is colored. In the Beach it resembles a pericarp. 



The bracts of the Catkin are usually called squamce or 

 scales, a term usually applied to any scaly appearance, and 

 the organ on which such scales appear is said to be squamose. 



The chatTon the receptacle of the compositaceae is another 

 form of the bract and they are caWed palecp. 



The Spathe is a bract which encloses the aggregated florets 

 of a spadix, as in the Arums. 



86. The kind of bracts which demands the most careful at- 

 tention of the student, if he expects to encounter with success 

 the large family of plants to which it belongs, is the form they 

 assume in the grasses. We believe the great and discourag- 

 ing difTiculties which are encountered by the student in his 

 very first elforts to analyze the plants of this importont and 

 interesting t'amily of vegetables, is owing, more than to any 

 thinfj else, to the failure in obtaininfj distinct ideas of the 

 terms used in their de-cription and of their application. 



Let the student take the Crab-grass Digitaria sanguinalis, 

 as a specimon for examination. I mention this, because it may 

 be found in all places included in this treatise, and in bloom 

 through the summer, and known by every body. Other speci- 

 mens might be taken, which would answer our purpose better 

 in some respects, but the student might be unable to discover 



