76 
IOWA ACADEMY OF SCIENCES 
Diamond Willow (Salix missouriensis Bebb) is common along the 
Missouri River in Western Missouri from which region it has extended 
its range northward along the river, and westward in the Republican, 
Platte and Niobrara river valleys to the western border (1^^). 
Common Cottonwood {Populus occidentalis (Ryd.) Britton) is very 
abundant in the Missouri forests, from which it has passed up the rivers 
across the state (15) to the western border and beyond. 
Family Tiliaceae. 
Basswood or Linden {Tilia americana L.) The wing is an extension 
and enlargement of the bract of the peduncle of the inflorescence. The 
several spherical, dry fruits at maturity are attached nearly at right angletj 
to this wing, which is slightly bent and twisted. At maturity the bract 
carrying the fruits separates at its ' ase from the tree, and when caught 
by the wind whirls horizontally, carrying its freight of seed-bearing fruitss 
often a distance of many metres from the parent tree. The linden occurs 
abundantly in the forests bordering the Missouri river southeast of 
NebrasKa, and it now extends up that river along the eastern edge of the 
state (16) along tne Niobrara river to Cherry county. It has extended up 
the valley of the Blue and Republican rivers on the south to Jefferson 
county, and the Platte river in the central portion of the state, to Nance 
"unty. 
Family Ulmaceae. 
The Vvnite Elm {TJlmus americana L.) is very abundant in the valley 
of the Missouri river southeast of Nebraska, and thence eastward to th* 
Atlantic Ocean. From the southeastern forest body of this species it has 
extended up the several river valleys into all portions of the state (17) 
to the western counties. 
Rock Elm iUlmus racemosa Thomas) occurs commonly in the forest 
belt bordering the IMissouri riveT* southeastward, and from this region 
it has moved upward along the eastern border of the state (18) and up 
the Niobrara river near the northern boundary. While it has been 
recorded from but tvo stations (Cass and Keya Paha counties) it is 
highly probable that it occurs somewhat sparingly and perhaps intermit- 
tently along the eastern and northeastern border. 
Red Eim (Uhnus fulva Michx.) is abundant in the Missouri river for- 
est area, from which it has spread westward up the river valleys nearly 
or quite half way across the state (19). Beyond this area a single station 
is reported in Frontier County. 
Hackberry {Celtis occidentalis L.). The globose one-seeded fruits are 
fleshy, and are in fact small drupes, much like thin-fleshed cherries. They 
are freely eaten by birds, and thus the seeds may be carried to consider-? 
able distances (even to many miles) from the parent trees. This species 
occurs abundantly in the Missouri forests, from which it has extended its 
range up the Missouri. Republican. Platte and Niobrara river valle 3 rs. 
across the plains (20) to the Rocky Mountains. 
