Treks of thk xVorthekn United States 145 



Microspore. The smaller of the two kinds of non-sexual 

 spores produced in the Hower, The microspore de- 

 velops into the male gametophyte. 



Microsporangium. A sporangium which produces the micro- 

 spores ; the incipient pollen sacs in the seed plants. 



Alidrib. The central rib of a leaf or other organ. 



Monadelphous. Stamens with united filaments. . 



Monecious. Having staminate and carpellate flowers on the 

 same plant. 



Alonosporangiate. Flowers bearing only one kind of spores; 

 a flower with only stamens or carpels. 



Mucronate. With a sharp abrupt point. 



Mucronulate. Slightly mucronate. 



Naturalized. Plants not indigenous to a region but having- 



become established as part of the flora. 

 Natural pruning. The process by which dead twigs and 



branches are separated from the tree by the formation 



of a collar or callus. 

 Nectary. A nectar-secreting organ. 

 Node. The place where two internodes join, normally with 



a single leaf or more. 

 Nut. x\n indehiscent one-seeded fruit with a liard or bony 



pericarp. 

 Nutlet. A very small nut. 



Obcordate. Inversely heart-shaped. 



Oblanceolate. Inversely lanceolate. 



Oblong. Somewhat longer than broad with the sides nearly 

 or quite parallel. 



Oosphere. The unfertilized egg ; the female gamete. 



Oospore. The fertilized egg. 



Ovary. The female organ of reproduction; an egg-producing 

 organ. 



Ovate. Shaped like the longitudinal section of a hen's egg. 



Ovulary. The ovule-bearing part of a closed carpel or set of 

 carpels. 



Ovule. The megasporangium of a seed plant which later de- 

 velops into a seed. 



Ovum, The egg or oosphere. 



