172 MONOCOTYLEDONS 



Type I. : YELLOW FLAG {Iris pseudacorus).* 



Vegetative characters. — A perennial herb with a creeping 

 sympodial rhizome. The leaves are mostly radical, sword-like, 

 and overlap in an equitant manner. Inflorescence. — The main 

 type of branching is cymose. Flower (figs. 216, 217) actino- 



morphic, ?, 

 p. 1^ \ \ cyclic, epigyn- 



ous. Perianth 

 3 + 3, united to 

 form a long 

 tube, pe'taloid, 



•'^"";^^ ^{'f~^ \f , Wli/^\J XM yellow. The 



r --^ :^iS"''*'ISjss,\M ll f^^^Smi^^milf free parts of 



the three peri- 

 anth - leaves, 

 which represent 

 the outer whorl 

 (P), are bent 

 downwards, 

 and each has a 

 narrow band of 



Fig. 2i6.— Flower of Yellow Flag. h^irs along itS 



middle line. The free portions of the inner perianth-leaves (/) 

 are smaller and incline upwards. Stamens (a) 3 -f- o, inserted 

 on the perianth opposite to the outer whorl of perianth-leaves ; 

 anthers extrorse. Carpels three, syncarpous, inferior; the 

 ovary (pv) three-chambered, with many ovules on an axile 

 placenta. The style {sy) is single below, but above it divides 

 into three broad flattened petaloid branches, which are opposite 

 to, and arch over, the three stamens (see also fig. 2 1 8). On the 

 surface of each band-like branch of the style there is a small 

 thin shelf isg), whose upper face is the stigma. The three 

 chambers of the ovary and the three branches of the style 

 are opposite to the three stamens. This fact convinces us that 

 the three carpels do not alternate with the three stamens. 

 Why are the carpels thus opposite to, or superposed on, the 

 stamens ? If we look at a floral-diagram of a Liliaceous plant, 

 and compare it with that of the Yellow Flag, we note that the 



* The flowers of other species of Iris grown in gardens are sufficiently 

 like the one here described, to be examined in place of the latter. 



