4z PLANT STUDIES 



itself (reproduction). To tlie great work of nutrition many 

 kinds of work contriJjute, and tlio same is true of repro- 

 duction. Nutrition aaid reprodueti((n, however, are tlie 

 two primary kiiuls of work, and it is interesting to note 

 that the first advance in the dilferentiation of a simple 

 plant body is to separate the nutritive and reproductive 

 regions. In the complex plants there are nutritive organs 

 and reproductive organs ; by which is meant that there are 

 distinct organs which speciallv contriljute to the work (jf 

 nutrition, a,nd others which are specially concerned with 

 the work of reproductinn. The ditferent kinds of work are 

 conveniently spoken of an functions, each organ having one 

 or more functions. 



7. Life-relations. — In its nutritive and )'eiiroductive work 

 the plant is very dependent upon its surroundings. It 

 must receive material from the outside and get rid of waste 

 material ; and it must leave its offspring in as favorahle 

 conditions for living as possible. As a consequence, every 

 organ holds a definite relation to something outside of it- 

 self, known as its lifc-relalion. For examjile, green leaves 

 are definitely related to light, many roots are related to 

 soil, certain plants are related to aliuiubint water, some 

 plants are related to other plants or aiumals (living as 

 parasites), etc. A plant with several organs, therefore, 

 may hold a great variety of life-relations, and it is cpiife a 

 complex proljlem for such a plant to adjust all of its parts 

 properly to their necessary rehitions. The study of the 

 life-relations of plants is a division of Bota.ny known as 

 Ecology, and presents to us manv of the most important 

 prol)lems of plant life. 



It must not 1)0 supposed that any plant or organ holds 

 a perfectly sim])l(.! lif<'-rolation, foi' it is affected 1)y a great 

 variety of things. A i-oot, for insta.nce, is afiiccted l>y ligbt, 

 gravity, moisture, soil material, (■oiita,(^f, etc. Everv oi-- 

 gaii, tlierefore, must a.iljust itself to a. vci'v conijilex si't of 

 life-relations, and a, plant with sevei'al oi-gaus has so many 



