254 BOTANY. 



herbaceous annuals to large woody perennials. It is a most 

 difficult matter to arrange so great a number of species 

 satisfactorily, so as to show their mutual relationship. 

 They have been grouped into about one hundred and sixty 

 orders. The orders, again, have been grouped as far as 

 possible in such a way as to bring together those which 

 bear the closest resemblance to one another. The disposi- 

 tion of these groups is as yet partly artificial, in many 

 cases resulting in the separation of orders which are evi- 

 dently related. 



534. The following synopsis will show the latest arrange- 

 ment, as generally adopted in this country. For conven- 

 ience three artificial groups are made, viz., Apetalse, Gamo- 

 petalse, and Choripetalae. 



I. APETAL2B. APBTALOUS DiCOTTLEDONS. 



Plants -whose flowers generally have but a single floral envelope 

 (calyx) this even, in some cases, wanting. 



Many of the orders here brought together are related to those to he 

 noticed further on. Their flowers are in many cases to be regarded 

 as simplified Choripetalse, or less commonly Gamopetalae. The 

 grouping given below is almost entirely artificial. 



Series I. . — Flowers mostly unisexual. Perianth none or 



small. A group of anomalous orders of doubtful relationship. 



Order 1. The Horn worts (Ceratophyllaccse) are a few small aquatics, 

 widely distributed. The seeds contain a well-developed embryo and 

 no endosperm. 



Order 3. The Crowberries (Empetracese). — These are four small 

 Heath-like shrubs producing berry -like fruits whose seeds contain a 

 small embryo in copious albumen. 



Order 3 (Lacistemacese), shrubby plants (16 species) of tropical 

 America, producing dry fruits whose seeds contain a copious endo- 

 sperm. 



Order 4. The Willows (Salicacese) are trees and shrubs common in 

 the Northern Hemisphere. They include also tlie Poplars, there being 

 150 or more species of true willows and 18 poplars now known. 

 Tlie flowers are unisexual, and the staminate and pistillate forma 

 always occur on different plants (i.e., tjiey are dioecious); they are 



