PAPERS ON BOTANY 135 
ARTIFICIAL KEY TO THE WEED SEEDS FOUND IN 
COMMERCIAL SEEDS IN ILLINOIS AND 
ADJOINING STATES 
Ricuarp ALonzo Gantz, Muncin, INp. 
INTRODUCTION 
The purpose of this work is to aid one to determine the 
weed seeds and seed-like-fruits frequently found in commercial 
grains of Illinois and adjoining states. The term, seed, in this 
key, is used to mean a ripened ovule. It is not used to include 
fruits such as an achene and caryopsis. If the structure is a 
fruit, it is named as such. 
Since the terms seed, fruit, schene, caryopsis, nut, nutlet, 
utricle, spike, spikelet and involucre are used, it is necessary 
to define them. A seed is a ripened ovule; e. g., wild mustard. 
A fruit is a ripened ovary with its attachments; e. g., common 
ragweed. An achene is a seed-like indehiscent fruit in which 
the seed is not firmly united with the wall of the ovary; e. g., 
curled dock. A caryopsis is a similar one seeded indehiscent 
fruit in which the seed is firmly united with the wall of the 
ovary; e. g., cheat. A nut is a dry indehiscent fruit usually 
one celled and one seeded, with a hard bony wall; e. g., hazel- 
nut. A nutlet is a diminutive nut; e.-g., wheat thief. A utricle 
is a small one seeded dry fruit with a thin bladdery loose ovary 
wall. When ripe the wall bursts and the seed is exposed; e. g., 
lamb’s quarters. A spike is a form of inflorescence with the 
sessile flowers arranged on an elongated common axis; e. g., 
wheat. A spikelet is a small or secondary spike. It may con- 
sist of a one seeded fruit, caryopsis, enclosed by coverings, 
which are scale-like, called lemma, palea, and outer lumes; 
e. g., yellow fox-tail. An involucre is a cluster of small leaves 
or bracts just below the flower. It may be modified and en- 
close an achene; e. g., common ragweed. 
The seeds and seed-like fruits were gathered during the 
years of 1916 and 1917 in Champaign County, Illinois. By ex- 
amining commercial seeds obtained from seed houses, by get- 
ting expressions from various seed-dealers, by consulting bul- 
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