34 



GARDENERS' CHRONICLE 



What is a Flower? 



WILLARD N. CLUTE 



TO ask ■■\Miat is a flower?'' seems at Hrst glance an 

 extremely foolish question. Anybody with average 

 intelligence ought to know what a flower is. If by 

 the term we mean the creations offered by the florist it is 

 probable that few would g'o astray in the naming, but if 

 we get down to e.xact science, and ask what the botanist 

 means by "flower" the matter is invested with more diffi- 

 culty. 



Are "Calla lilies" flowers? Xo, they are bunches of 

 flowers. Are dandelions flowers? Xo, they might be 

 regarded by the botanist as a bouquet but never as 

 single flowers. How about the sunflowers? The case 

 is still worse, for the sunflower is really a bouquet of 

 two kinds of flowers. Are pussy-willows flowers.-' .\'o, 

 they are onlv half flowers, while the "flowers"' of the 

 flowering dogwood are a bunch of flowers plus, and so 

 are those of the poinsettia. The "flowers" of the piiinted 

 cup are colored leaves and so it goes. 



Everybody knows, of course, that the seaweeds and 

 other algas, the fungi, lichens, mosses, liverworts, ferns 

 and various other low forms of life have no flowers at 

 all, otherwise there would be no distinction in calling 

 one branch of vegetation "flowering plants." But a good 

 many true flowering plants might be put in this flower- 

 less list by a student unfamiliar with their peculiarities. 

 For instance, let us take the case of Wolfiiia. When 

 full grown the plant is about the size of a period on this 

 page. One has to use a microscope to get much of an 

 idea of it, and yet it is a member of the flowering plant 

 group in good and regular standing. It is true that its 

 flowers consist of a single stamen and carpel each, but 

 these suffice for the plant's needs in this line for the 

 two organs mentioned originate the pollen grains and 

 ovules which in turn produce the sperms and eggs which 

 unite to form new plants. This, indeed, is all that any 

 flower is for, and though other plants may have addi- 

 tional parts, just as rich men may have more servants 

 than others, these extra parts are seen to be superfluous 

 for the plants can get along very well without them. 



Wolfifia is our smallest American flowering plant, but 

 there are other and larger species with flowers nearly 

 as simple. In the grasses, sedges, cat-tails, and tlie great 

 majority of our forest trees, the blossoms are similar in 

 structure, though there are likely to be more of each kind 

 of organ. A great many people are surprised to know 

 that such plants bear flowers at all. The blossoms of the 

 poplars, willows, birches and some others arc rather more 

 conspicuous and therefore m(}re familiar sights, but it is 

 seldom that the non-botanist sees any connection be- 

 tween these and the fruiting of our forest trees. The 

 idea held by many seems to be that acorns, pine cones, 

 and hickory- nuts just happen. 



One peculiarity of these simple flowers is that the 

 stamens and carpels are frequently borne on different 

 plants. This is true of the willows and jjopulars where it 

 takes two separate trees to produce a single ripe seed. 

 Such sfjecies are spfiken of as ditecious, and the clusters 

 of stamens and carpels are known as staminate and car- 

 l^ellate flowers respectively. The la.st mentioned may also 

 i)e called pistillate flowers, but carpellate is a better term. 

 In ])ine-;. oaks, walnuts, chestnuts and numerous others. 

 the staminate and carpellate flowers are borne on the 

 same plant but in different places. This is well seen in 

 the common cat -tail where the stamens are alK)ve tlie car- 

 pels on the same stalk, .\fter jirdducing the pollen tin- 



stamens fall off but the carpels remain and ripen up into 

 the c_\-lin(lrical brown mass of fruits with which we are 

 all familiar. ]\Iaize or corn is another good example. 

 Here the tassel consists entirely of staminate flowers and 

 the ear of carpellate ones. When young, an ear of corn 

 is really a bunch of flowers ! Or, perhaps it might be 

 l>etter to say a bunch of half-flowers since complete flow- 

 ers are regarded as consisting of lx)th stamens and car- 

 l>els. Again, a pine-cone is a cluster of ripened carpels. 

 In Spring, however, the pine tree bears a second set of 

 cylindrical, cone-like objects which ultimately open and 

 shed clouds of pollen on the air and thus prove them- 

 selves to be staminate flowers. When staminate and car- 

 pellate flowers are borne on different parts of a single 

 plant, the species is said to be monoecious. In addition 

 to the arrangements thus far mentioned, various other 

 plants may have three kinds of flowers, staminate, car- 

 pellate and a mixture of both stamens and carpels. In 

 no case, however, is there a species of flowering plant 

 that lacks either stamens or carpels, though as we have 

 seen, certain individuals may lack one or the other. 



In the older books the stamens and carpels are called 

 the essential organs because both are absolutely necessary 

 to the production of seeds. Probably a better name for 

 these organs is sporophyll since it is now known that the 

 jxillen grains borne by the stamens and the ovules borne 

 by the carpels, are spores. All the flowering plants must 

 possess these parts no matter how many accessories they 

 may have in the way of petals, sepals, coronas, nectaries, 

 bracts, spurs, and disks. These extra parts may help the 

 stamens and carpels in carrying on their work, hut they 

 are not necessary. 



One has to go back to the ferns to understand how 

 we are warranted in calling the so-called essential organs, 

 sporophylls. In the ferns, it is well known that some of 

 the leaves bear small dustlike objects which are known 

 as spores and which reproduce the plant. Such leaves 

 are called sporophylls to distinguish them from the ordi- 

 nary vegetative or foliage leaves. In other fernworts, 

 though the sporophylls are alike, the spores do not pro- 

 duce plants of the same sex when they germinate. The 

 best nourished are likely to produce eggs and the less 

 vigorous bear sperms. In still other members of this 

 group there is a difference in the size of the sporophylls 

 and a corresponding difference in the spores. The small 

 s])ores ])ro(hiced by the small sir>rophylls give rise to 

 plants bearing sperms while the larger sporophylls of 

 course ultimately produce eggs. Thus when we come to 

 true flowers we see the same two forms of sporophylls, 

 a little miore refined, a little more distinct, and a little 

 more efficient, but still sixirophylls. They are arranged 

 on the flowering .stem, as leaves are arranged in rosettes, 

 and may, on occasion, turn to leaves. Indeed, it is tjuite 

 likely that we have the whole matter reversed and that 

 leaves have been derived from sporophvlls or perhaps 

 both sporophylls and leaves have originated from some 

 more primitive form. The botanist is fond of saying that 

 a flower is a branch be.set with sporophylls. and this 

 comes pretty near to answering the ref|uirements. In 

 accordance with this, however, it wduld -icem as if some 

 of the fernworts might qualify as flowering plants. None 

 III these latter j^lants, however, bear seeds, and seeds are 

 the really distinguishing features of that highest di\ision 

 of the vegetable kingdoni. which we conuiionly call flow- 

 ering plants. 



