386 YEW ; CYCAS. 



the sac curls outwards, so that the stamen appears like an umbrella 

 turned inside out, the pollen remaining in the pocket-like cavities 

 until removed by the wind. 



542. Female Flower. The female flower is also 

 formed from a bud arising in a similar position to that of 

 the male, but the single ovule does not arise directly from 

 the axis of this bud it stands at the end of a very short 

 branch arising just below the apex of the bud. The bud 

 bears about ten spirally arranged scales, and in the axil 

 of the uppermost scale there arises a small branch, which 

 pushes aside the true apex ; this little branch bears three 

 pairs of opposite scales and ends in an ovule. 



Cut longitudinal sections of the bud, which is easily 

 recognised on the female tree by its position on the 

 underside of the twig, and its ovoid and pointed shape, 

 and try to make out the arrangement just described. 

 From the micropyle there oozes a drop of sticky liquid, by 

 which the pollen-grains are caught when the flower opens. 



543. L.S. of Ovule, etc. In a median longitudinal section of 

 the ovule, taken in March, note (1) the single integument with 

 the micropyle ; (2) the nucellus, forming the termination of the 

 axis of the female shoot ; (3) the embryo-sac or megaspore. 

 placed deeply in the nucellus ; (4) the aril, a small ring-like out- 

 growth around the base of the integument, i.e. seen in section as a 

 short projection on either side. 



In sections taken later in summer, note (1) the endosperm; (2) 

 the archegonia ; (3) the single embryo formed from the oospore ; 

 (4) the growth of the aril, which eventually protudes beyond the 

 integument. The aril, at first green, forms a bright red fleshy cup, 

 covered with waxy bloom, and invests the hard brown or purplish 

 seed giving a superficial resemblance to an acorn and its cup. 



The embryo has two cotyledons, which, like the spirally 

 arranged leaves that succeed them in germination, resemble the 

 ordinary foliage-leaves formed later. 



CYCAS. 



544. Cycads. Cycas and its allies, forming the 

 Cycadaceae, are tropical and subtropical plants, most of 

 the living members of this family being rare and very 

 locally distributed, though in ancient times (especially in 



