Colorado Agricultural College 
7 -^ 
Key to Species 
♦Seeds ribbed I . .Iva ciliala 
♦Seeds not ribbed 
Seeds usually angled, 1.5-2 mm. long t..Iva xanthifolia 
Seeds seldom angled, 2-3 mm. long 2.. Iva axillaris 
1. Rough Marsh Elder {Iva 
ciliata Willd.) (Fig. 138). — Seeds 
smoke-gray to deep grayish-olive in 
color, flattened, thin, each face marked 
with 2 or 3 ribs as long as the achene ; 
seeds either broadly oval or pear- 
shaped, 2.5-3,5 mm. long, 2-3 mm. wide, 
in the widest part. 
2. Common Marsh Elder {Iva 
jianthifolia Nutt.) (Fig. 139). — Seeds 
neutral-gray to dark neutral-gray in 
<?olor, somewhat rounded on each side, 
usually obscurely angled on one side; 
seeds uniformly cuneate in shape, 1.5-2 
mm. long, 1-1.5 mm. wide, in the widest 
part, marked with numerous fine 
parallel lines as long as the seed. 
Fig. 139. Common 
Marsh Elder (Iva 
xanthifolia). x 12. 
fhg. 138. Rough Marsh 
Elder (Iva ciliata). x 13. 
Fig. 140. Pov- 
erty Weed (Iva 
axillaris), x 11. 
3. Poverty Weed, Sm. all-flowered 
Marsh Elder {Iva axillaris Pursh.) (Fig. 
140). — Seeds deep mouse-gray to iron- 
gray in color, rounded on each face, not 
angled, uniformly cuneate in shape, 2-3 
mm. long, 1.2-1. 5 mm. wide, in the widest 
part. 
33. THISTLE FAMILY 
{Compositac, Cardiiaccae) 
Fruit an achene; pappus consistino- of bristles, awus, scales, 
teeth, or cup-like crown, or absent; seeds erect; endosperm absent: 
embryo straight. 
