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

 GLOSSARY 



A-: A prefix ("alpha privative") sig- 

 nifying " not," as in apetalous, asep- 

 alous, asymmetrical, etc. 



Abortive: Imperfectly formed or de- 

 veloped ; rudimentary ; hence sterile. 



Acaulescent: Without a true or leafy 

 stem; having the leaves in a basal 

 tuft, the flowers or flower head 

 borne on a stalk (pedicel, peduncle, 

 or scape) from the ground. Thus 

 the common dandelion is acaules- 

 cent. 



Acerose: Having a hard, sharp, needle- 

 like tip. 



Achene (pronounced ay-keen') : A 

 small dry 1-seeded 1-celled inde- 

 hiscent fruit; the fruit of sedges, 

 buttercups, composites, etc. (Fig. 1.) 

 Sometimes spelled akene. 



Figure 1. — Achenes of 

 (A), a sedge {Carex 

 sp.) ; (B), sunflower 

 (Helianthiis annuus) 



Acicular: Needle-shaped, as the leaves 

 ("needles") of a pine tree. 



Acorn: The characteristic, 1-celled, 

 1-seeded fruit of oaks (Quercus 

 spp.) ; it consists of a cuplike part 

 called the cup, cupule, or involucre, 

 and the glands or nut which con- 

 tains the embryo. 



Aculeate: Beset with prickles (aculei), 

 as a rose or gooseberry bush. 



Acuminate: Tapering gradually at the 

 end, or apex ; taper-pointed ; long- 

 acute. (Fig. 2, A.) 



Figure 2.— Three types of leaf 

 tips : A, acuminate; B. 

 acute ; C, obtuse. Other 

 types are illustrated in Fig- 

 ures 5 and 29 



Acute: Terminating sharply and 

 abruptly in an angle of less than 

 90°. (Fig. 2, B.) 



Adnate: Literally " grown to" or " ad- 

 herent to"; said of parts that are 



attached throughout their entire 

 length to other parts of a different 

 •series; an adnate anther is so at- 

 tached to its filament. 



Adventitious: Said of buds produced 

 without order or in an unusual place 

 on any part of a plant. 



Adventive: A waif; a plant uninten- 

 tionally introduced from another 

 locality but not truly naturalized. 

 Used both as a noun and adjective. 



Akene: Same as achene. 



Alate: Winged ; provided with " wings " 

 (Latin, alae), or winglike append- 

 ages, as, for example, the fruits of 

 maples, angelicas, and fourwing 

 saltbush. 



Alternate: Placed singly, not oppo- 

 sitely nor in pairs; first one and 

 then another, as leaves on a stem. 



Alternation of generations: The alter- 

 nation of gametophyte and sporo- 

 phyte in the life history of a plant 

 species. Ferns furnish a familiar 

 example of this phenomenon (which 

 is sometimes called heterogenesis) ; 

 the gametophyte (plant which bears 

 the sex organs) is a minute, flatfish, 

 green plant (called the prothallus 

 or prothallium ) , whereas the asex- 

 ual generation, the 

 sporophyte, is the 

 large plant o r d i- 

 narily recognized 

 as a fern. This 

 phenomenon is one 

 of great scientific 

 and evolutionary 

 interest and, in 

 modified form, oc- 

 curs in the higher 

 plants as well. It 

 occurs also in the 

 a n i m a 1 world, 

 the hydroid jelly- 

 fishes and medusas 

 being well * known 

 examples. 



Ament: A bracted, 

 pendulous spike ; 

 a catkin; as in 

 birches, alders, 

 poplars, oaks, etc. 

 (Fig. 3.) 



Amphitrop ous : 

 Half anatropous ; 

 said of ovules hav- 

 ing a short raphe, 

 the hilum, or place of attachment, 

 about in the middle of one side of 

 the ovule. 



Anabolic: Of or pertaining to anabol- 

 ism. 



Anabolism: That phase of metabolism, 

 or the life processes of plants, which 



Figure 3. — Ad 

 ament, or eat- 

 k i n , as in 

 birch (Betula) 



