146 The Mechanical Structure of l^lants. 



that hath a stiff, strong, stem, that is able to mount up and stand alone without 

 assistance furnished with these tendrils." We make a single, simple cjmparison, the 

 pea and the bean, and remark that in the pea they do not make their appearance till 

 the plant has grown to a height to need support. 



The hollow stems of canes, straws and grasses, give the greatest possible amount 

 of strength and elasticity for the amount of material used. Joints at stated distances 

 in these tubes are another element of strength without increase of weight, the 

 material being slightly different. With what uniformity and care has nature pro- 

 vided for these stalks of grasses, grains, and canes, by covering each with an im- 

 penetrable coat of weather proof varnish. 



Grasses seem to be nature's especial care. With these she carpets her green 

 earth and paints the landscape ; with these she feeds the human family, the birds of 

 the air, beasts of the field, and the grub beneath the surface. Cattle feed upon the 

 leaves, birds upon the smaller seeds, many insects upon their roots, and none need 

 be told that corn, wheat, rye, etc., etc., are strictly grasses. 



Corn is a monoecious panicious grass, and though the great staple of the west, it 

 seems to be overlooked in its botanical and mechanical constructure by intelligent 

 growers. Our bread producing plants are grasses. Those families of plants known 

 as grasses, exhibit extraordinary means and powers of increase, hardiness, and an 

 almost unconquerable disposition to spread their faculties for recuperation coincide 

 with the intention of nature concerning them. They thrive under a treatment by 

 which other plants are destroyed. The more their leaves are consumed, the more 

 their roots increase. 3Iany seemingly dry and dead leaves of grasses revive and 

 renew their verdure in spring. In lofty mountains and cold latitudes where the 

 summer heats are not sufficient to ripen their seeds, grasses abound whichiare able 

 to propagate themselves without seed. The number of the mechanical adjustments 

 are so numerous, we must content ourselves as before remarked with a reference to 

 the more common and marked instances. Parasitical plants furnish marked illustra- 

 tions. The Cuseuta Europea is of this class. The seed opens and puts forth a 

 little spiral body which does not seek the earth to take root, but climbs spirally from 

 right to left upon other plants from which it draws its nourishment. The little 

 spiral body proceeding from the seed is to be compared with the fibres, the seeds 

 send out in ordinary cases. They are straight, this is spiral. They shoot down- 

 wards, this shoots upwards. In the rule, and in the exception, we equally perceive 

 the design. 



A better known parasitical plant is the mistletoe. We have to remark in it a 

 singular instance of " compensation." No art hath yet made those plants root in the 

 earth. Here, then, might seem to be a mortal defect in their constitution. Let us 

 examine how this defect is made up to them. The seeds are endued with an 

 adhesive quality so tenacious, that they adhere to the surface or bark of any tree, 

 however smooth. Roots springing from these seeds insinuate their fibres into the 

 woody substance of the tree from which this parasite draws its life and maintenance. 

 Another marked instance of rare mechanical action is in the Autumnal Crocus 

 [Chohicum autumriale). How I have sympathized with this poor plant. Its blossom 

 rises out of the ground in the most forlorn coadition possible, without a sheath, calyx, 



