The Scottish Naturalist. 6 1 



point to the earlier and simpler condition of the plant's history, 

 before its vital needs had brought about the adaptational changes 

 that disguise the genetic resemblances of the different forms. 



The marked differences that exist in the leaves of the conspicu- 

 ously heterophyllous plants, e.g., Ranunculus aquaticus or Helo- 

 sciadium inundatum, are known to almost everyone, and are 

 usually to be found represented in collections, though often enough 

 rather poorly ; but there are many other plants that are more or 

 less heterophyllous, but that do not get the same care bestowed 

 on them. Of such species many examples might be mentioned, 

 e.g., Ranunculus auricomus, Pimpinella Saxifraga, Scabiosaar vensis, 

 not to refer to more commonly quoted examples. Obviously any 

 collection that fails to show these parts is defective in at least one 

 or more very important respects. 



A cursory glance at any descriptive work on the flora of any 

 land, at once shows that characters of value in distinguishing 

 species are obtainable frequently from the form and structure of 

 the underground parts of plants. In these species it is clearly 

 essential to have such parts shown in the collection ; but in all 

 cases, where at all manageable, subterranean parts ought to be 

 properly shown along with the rest, despite their unsightly appear- 

 ance at times. In the parasitic species of Phanerogams, the value 

 of the specimens is much enhanced by the connection between the 

 host-plant and the parasite being clearly shown in the herbarium, 

 though this is seldom seen. In fact, in the semi-parasites, such as 

 Rhinanthus, the parasitism is generally forgotten entirely. 



In other plants, e.g., the Lesser Celandine, there are special bodies 

 produced at certain seasons for reproduction, which in the plant 

 named take the form of axillary tubers; while a viviparous condition 

 is by no means unfrequent in certain plants, depending for its 

 frequency, in some degree, on local or climatic causes. 



The importance of the flowers is generally sufficiently recognised 

 to render it needless to dwell upon them as essential ; but in very 

 few herbaria is there any attempt made to show the development 

 of the parts of the flower ; despite the value of development as a 

 clue to genetic relationships, and thereby to the determination of 

 a really natural system of classification. It is often hardly possible 

 from a dried plant as a whole to ascertain readily, without injuring 

 the specimen, such points as the nature of the inflorescence; and 

 naturally it is still more difficult to see the form and relations of the 

 parts of the flower. ♦Structural characters like these are best made 

 available by special preparations accompanying the entire plant. 



