ic>4 LIFE ; OUTLINES OF GENERAL BIOLOGY 



and dry. may be practically the same. The fruit is the ripe ovary or 

 seed-box, often with the addition of accessory parts, such as the top 

 of the floral axis. The seed is an embryonic plant in a state of arrested 

 development, often equipped with food-material, and it lies within 

 the seed-box. The anatomical distinction is clear, and yet it may be 

 unimportant ecologically. Thus the familiar wind-borne fruit of the 

 dandelion consists of a delicate lilament with a nutlet at the base 

 and a iKMUtiful parachute of radiating hairs at the tip. What is 

 IcKlged in a crevice of the soil is the nutlet fruit, which contains a 

 single seed. Fruit and seed are in such cases practically identical. 

 The same is true of other nutlet-fruits or achenes, such as those of 

 grasses. Similarly there is a group of dry fruits (schizocarps) which 

 do not open, as jwds and capsules do, but divide into a number of 

 pieces each with a single seed. In technical i)hrase they are indehis- 

 cent. yet they break into "merocarps", each usually with a single 

 seed. The fruits of hemlock and of Labiates arc of this type. What is 

 sown is a piece of fruit, and when sprouting occurs the seedling has 

 to tind its way not only out of the softening seed-envelopes, but out 

 of the decaying wall of the fruit-fragment. 

 The majority of fruits are included in the following five groups. 



(i) The box fruits or capsules break open or dehisce to some 

 extent when mature or moribund, and thus allow the seeds 

 to escape. The simplest is a pea-pod or legume, consisting 

 of a single folded carpel or sporophyll ; the siliqua, character- 

 istic of Crucifers, is built up of two carpels; the pansy fruit 

 of three; and so on. Most complex are capsules like poppy- 

 heads, where the dehi.sccnce takes the form of a ring of little 

 holes, tlirough which the seeds tumble out. In many cases 

 the lid of the capsule falls off when the seeds are ripe. The 

 most imjx)rtant fact is that the dehiscence of the carpels is 

 to be ranked beside the withering, wrinkling, and fall of 

 foliage leaves, for carpels are transformed foliar organs. 



(2) Schizocarps or "Splitters" are dry indehiscent fruits, hke those 

 of rmbellifera.' and LabiatcT, which divide into a number 

 of pieces, each usually containing a single seed. The seeds 

 do not escai>e from their fruit-enclosure, yet the fruit splits 

 into pieces. 



i\) A third group of dry fruits includes the true nuts, and nutlets 

 technically called achenes. They do not open to liberate the 

 .s<ed. neither do they split into pieces. Indeed, they are 

 usually single-seeded. A true nut is well illustrated by the 

 hazel-nut. with a very hard fruit-wall to which the seed is 

 not adherent. In the seed-like fruits of a buttercup the wall 

 is not hard and the seed— not very difficult to pick out- 

 lies freely within. In the grain of wheat, the fruit-wall is 



