MORPHOLOGY OF FLOWERING PLANTS. ] 3 



produce pollen, and the carpels of the female cones produce ovules ; 

 but the carpels, occur in the form of open scales, and the ovules 

 are borne upon the surface or the free margins of the carpels, so 

 that the pollen reaches them at once, without passing through 

 a stigma and style. Plants with flowers of this kind, with 

 which are also associated many peculiarities in the mode of deve- 

 lopment of the embryos, are called Gymiwspermous, or naked- 

 seeded. 



Much difference of opinion still exists among botanists as to the true 

 nature of the female flower in Gymnospernis ; but for the present the above 

 explanation will suffice for the student. 



The Angiosjpermia, comprehending the great body of the Flower- 

 ing plants, are separable into two very natural groups, which are 

 plainly distinct in the mass, although many complex relations exist 

 between them. Distinctive characters of the two divisions may be 

 found in many parts of the organization of the majority of the 

 plants ; but the most general difference is that which occurs in the 

 structure of the embryo contained within the seed. 



In one division we find that the seeds, with few exceptions, con- 

 tain an embryo in which we may distinguish two rudimentary leaves, 

 or cotyledons, applied face to face, and having the terminal bud, or 

 growing-point of the stem, enclosed between them. In the other 

 division the embryo presents but one cotyledon, or seed-leaf, more 

 or less rolled round the bud, like a sheath. The plants of the first 

 division are called Dicotyledonous, those of the second Monocoty- 

 ledonous. 



Dicotyledons and Monocotyledons are naturally divided from 

 each other not only by the general characters of their mode of 

 germination, but by the structure of their stems, the arrangement 

 of the skeletons or veins of their leaves (net-veined in Dicotyledons, 

 parallel or straight-veined in Monocotyledons), and the number of 

 organs in the circles of the flowers (generally in fours or fives in 

 the one case, and in threes in the other). These distinctive cha- 

 racters will be more fully considered hereafter. 



The ripe seed of the G-ymnospermia is very much like that of 

 Dicotyledons ; but the leaves of the embryo are either more nume- 

 rous, or if but two are present, they are sometimes, but not always, 

 slit into lobes, whence these plants h a ve been called Poly cotyledonous. 



The germination of the seeds of all the Flowering plants con- 

 sists in the emergence of the embryo, more or less completely, from 

 the seed, and in the unfolding of its rudimentary vegetative organs 

 the radicle, the cotyledonary leaf or leaves, with the stem supporting 

 them, the tiyellum, which is sometimes very short, but which termi- 



