AGGREGATE FLOWERS. 



37 



peduncles, footstalks*, as in Scabiosa, Knautia, Dipsacus, Ce- 



PHAfcANTHUS, GlOBULARIA, LEUCADENDRON, PrOTEA, BrUNIA, 



Barreria, and Statice. ' 



2. A Compound flowerf is an aggregate one, comprehending 

 many florets that are sessile, without peduncles, on a common re- 

 ceptacle that is entire, and having also a common perianthium, 

 but furnished with antheras that grow 1 together in the form of a 

 cylinder. 



The properties of a compound flower are, 1. A common recep- 

 tacle enlarged and undivided. 2. A common perianth ium, sur- 

 rounding all the florets. 3. The florets monopetalous and ses- 

 sile. 4. The antherae of each floret five in number, and growing 

 together in a cylinder. 5. A monospermous germen under each 

 of the florets. Of these properties, the two last are essential to 

 a compound flower ; but observe, that there are some whose 

 calyx contains only a single floret, as Echinops, Stcebe, Corym- 

 bium, and Artemisia. 



Compound flowers are of three kinds: 1. Ligidate, when all 

 the corolhdce, little corolla of the florets, are plane, flat, shaped 

 like ligula, a narrow tongue, or fillet, and expanded towards the 

 outer side. 2. Tubidose, when all the corollulae of the florets are 

 tubulose, and nearly equal. 3. Radiate, having rays, when the 

 corollulae of the disk, middle parts, are tubulose, and those of 

 the circumference, margin, of another form : which variation af- 

 fords three cases, viz. when the corollulae of the circumference 

 are either ligulate, as in Achillea ; ...tubulose, but unlike the tu- 

 bulous florets of the disk, as in Centaurea ; ...or naked, as in Ar- 

 temisia and Gnaphalium. A compound flower usually consists 

 of many florets, but rarely of a determinate number of them. 



3. An umbellate flower is an aggregate one, consisting of 



* Peduncle is the foot-stalk of a flower only ; the foot-stalk of a leaf is called a 

 petiole. 



f These are the flowers of the class Syvgenesia, see Part II. Chap. XXII. 



