12 



MISC. PUBLICATION 110, U. S. DEPT. OF AGRICULTURE 



Disk: An enlargement or prolongation 

 of the receptacle of a flower around 

 the base of the pistil ; also, the head 

 of tubular flowers in composites. 



Dissected: Cut deeply or divided into 

 numerous and usually narrow or fine 

 lobes or segments. 



Distichous: Arranged in two ranks. 

 Thus, the leaves and floral bracts of 

 true grasses are distichous. 



Divaricate: Diverging at a wide angle : 

 widely spreading. 



Divided: Having the main divisions ex- 

 tending quite to the midrib or 

 rachis. A divided leaf is. therefore, 

 a compound leaf. (Figs. 12 and 13.) 



Dm.: Decimeter ( s ) , approximately 4 

 inches. 



Dorsal: Upon or relating to the back 

 or outer surface of an organ. 



Drupe: A simple, fleshy, or pulpy 

 fruit, the inner portion of the peri- 

 carp being hard and stony. A stone 

 fruit. The fruits of the peach, plum, 

 and cherry are familiar types of 

 drupes. 



Ecesis: The adjustment of a plant to a 

 new habitat and its establishment 

 therein. The result of a successful 

 migration. 



Ecology: That part of biology which 

 deals with the relationships of or- 

 ganisms to their respective habitats. 

 Literally, the science of home ( habi- 

 tat). Plant ecology includes the 

 study of all the factors in the en- 

 vironment of the individual plant 

 and of groups of plants and the ef- 

 fects which these various factors 

 have on the forms of plants, their 

 life history, succession, etc. 



E. g.: For example (Latin, exempli 

 gratia ) . 



Elliptic : With the outline of an ellipse. 



Emarginate: Notched or indented at 

 the apex. (Fig. 29. B.) Obcordate 

 is more deeply and refuse more shal- 

 lowly notched. 



Figure 29. — Types of leaf tip : A, 

 Retuse ; B, emarginate ; C, obcor- 

 date 



Embryo: The rudimentary, undevel- 

 oped plant (sporophyte) in a seed. 

 resultant from the union of a stam- 

 inate (male) and a pistillate (fe- 

 male) cell ; it ordinarily consists of a 



radicle (embryo stem), one, two, or 

 more cotyledons (seed leaves), and 

 a plumule (minute bud). This last 

 indicates where the stem and next 

 leaf or leaves of the germinating 

 seedling will be developed. 



Emergence: A growth outward from 

 beneath the epidermis. The prickles 

 of a rose stem, the ligule of a grass, 

 the corona of a milkweed or daffo- 

 dil blossom are examples of emer- 

 gences. 



Emersed: Raised above the surface of 

 the water instead of floating on it; 

 said of certain aquatic plants, es- 

 pecially their leaves and stems. 



Endemic : Indigenous or native in a re- 

 stricted locality ; confined naturally 

 to a certain limited area or region. 

 Thus. Silene ingrami is endemic in 

 the Uinpqua National Forest region 

 of southwestern Oregon. 



Endocarp: The inner layer of a peri- 

 carp, or covering of a fruit. The 

 bony part of the stone of a cherry or 

 plum, for example, is botanically an 

 endocarp. 



Ensiform: Sword shaped. 



Entire: Without teeth, lobes, divisions, 

 or any marginal cutting ; having a 

 smooth and uninterrupted, flowing 

 outline. (Fig. 30. A.) 



A B C D E F 



Figure 30. — Six types of leaf margin : 

 A, Entire ; B, serrate ; C, dentate ; D, 

 undulate or repand ; E, crenate ; F, 

 incised 



Ephemeral : Enduring for a day ; eva- 

 nescent. As the ephemeral flowers of 

 many cacti, which wither the day 

 after blooming. 



Epicarp: The outermost layer of a 

 fruit, especially in a 3-layered fruit 

 covering. 



Epidermal: Of or pertaining to the 

 epidermis. 



Epidermis: Literally overskin. The 

 thin outer cell layer in the higher 

 plants, roughly analogous to the 

 epidermis of animals, usually pig- 

 nv?nted but mostly without chlor- 

 oplasts, and universally present in 

 leaves and herbaceous stems. 



