62 
Colorado Agricultural College 
Key to Genera 
seed armed with barbed prickles \"luhmpermnm 
j^eed smooth or wrinkled, unarmed 
1. Stickseed, Burseed 
(Lappula (Riv.) Moench) 
Fruit composed of 4 nutlets; nutlets armed with barbed prickles along 
the edge and sometimes with smaller ones on the rounded side (dorsal sur- 
face), the flat sides roughened with short hard processes. 
Key to Species 
. . 1..L. cupulata 
Seeds with a cup-like depression ^ ^ occidentalis 
Seeds without a cup-like depression 
1 Stickseed, Hairy Stickseed (Lappula 
cupulata (A. Gray) Rydh., Lappula texana 
(Scheele) Britton) (Fig. 112).— Seeds buck- 
thorn-brown in color, margin with 8-10 spines 
at regular intervals around the deep, cup-like 
depression ; the rounded or dorsal side of the 
seed tapers to a point and is marked by short, 
rough projections, and a distinct ridge extend- 
ing from the apex or center to a cleft in the 
spilled margin; seeds nearly circular in outline, 
1.5-2. 2 mm. across the flat face, including the 
spines. 
Fig. 112. Stickseed 
(Lappula cupulata). x 1- 
2. Stick WEED, Sticktight (Lappula occidcn- 
tali>i (8. Wats.) Greene) (Fig. 113). — Seeds buck- 
thorn-brown in color, margins with 10-15 stout 
spines lighter in color than the remainder of the 
nutlet ; the rounded side of the seeds tapering to 
a point, is marked with distinct, rough projections 
and a ridge nearly as long as the rounded face, the 
other side is marked with a few, scattered, blunt 
projections; the spines either extend straight out 
from the margin or directly downward ; seeds about 
2 mm. long, 1 or 1.5 mm. wide, including the spines. 
K 12. ^ 
2. Gromwell, Piiccoon, Indian Paint 
( Litkospcrmum ( Tourn . ) L.) 
Nutlets smooth, wrinkled or rough, hard or stony, often shiny and white, 
or nearly so. 
Narrow-leaved Puccoon (Litho- 
spri'iii ii'Di I invarifoliuni Goldie., 
Litlioxpcnn i/ in a r a ir k t i f o I i u m 
Michx.) (Fig. 114).— Seeds shiny, 
palc-olive-gray to white in color, 
ildged on one side, obscurely pitted, 
pointed at one end, truncate (as 
though cut off transversely) at the 
other; circular in cross-section; 
2.5-4 mm. long, 2-2.5 mm. Avide, in 
the widest imrt. 
I'ig. 113. Stickseed 
(Lappula occidentalis). 
Fig. 114. Narrow-leaved Puccoon 
(Lithospermum linearifolium). A. Bot- 
tom view. B. Top view. 12. 
