Before.  The trees mentioned in the journals May 14 – July 10, 1804, before reaching the Nebraska border, include  Ash, Buckeye, Cedar, Cottonwood, Crab apple (mentioned in one area only), Hackberry (mentioned once), Hickory, Honeylocust, Maple / Sugar tree, Mulberry, Oak, Pecan (mentioned in one area only), Pine (mentioned only once), Sycamore, Black Walnut,  White Walnut / Butternut, and Willow.  On the return trip, the fruit of the Pawpaw tree was ripe and it was a favorite of the men.

Here.  The trees mentioned during the period covered herein, July 11 - September 8, 1804, include  Ash, Cottonwood, Elm, Hackberry, Hickory, Honeylocust, Kentucky Coffeetree/Coffeenut, Basswood/Linden/Lynn, Maple, Mulberry, Oak, Cedar/Red Cedar, Sycamore, Wahoo/Arrowwood, Walnut/Black Walnut, and Willow.   These were familiar to the men, though which species they saw is sometimes not known.

After.  The trees mentioned within 10 days after turning into South Dakota include  ‘some indifferent’ Ash, Red Cedar, Cottonwood, Elm, ‘shrubby’ Oak, and Burr Oak.  They also saw Ponderosa Pine cones floating down the White River, though they would not discover the tree until later.  In all, Cutright would credit them with 35 trees that were new to science.

Except for Willows, no trees in our time period of  July 11 - Sept. 8, 1804, were mentioned by name until July 17th, when they were in waters bordering on Iowa.

Ash, Fraxinus sp.  
Noted only twice, July 30, and by Ordway Aug. 24.  Yet Green Ash was one of the contenders for the state tree of Nebraska.  The Green Ash and the White Ash often have 7 leaflets on the stem.

Basswood / Linden / Lynn, Tilia americana L., American Basswood. 
Noted July 30 and Sept. 4, by Clark and Ordway.

Cottonwood, Populus deltoides Marsh., Eastern Cottonwood. 
Noted many times.  It came to be one of the main trees seen as they ascended the River, and as they proceeded on, it would become important to them, for instance, it provided all the building material for Fort Mandan the coming winter, and logs for making canoes the next spring.  As they traveled farther, they would find the the Plains, Narrowleaf, and Black Cottonwoods, all three new to science; in fact, Moulton mentioned September 1st that they might be encountering the Plains Cottonwood which is a subspecies of Populus deltoides.  One species or another of Cottonwood is found in almost every state.  The Eastern Cottonwood is the state tree of Kansas and Nebraska.

Elm,  Ulmus americana L., the American Elm. 
Noted 10 days, July 18 – Sept. 4, by Clark and Ordway.  The American Elm is the state tree of North Dakota.

Hackberry, Celtis occidentalis L. 
Noted once, Sept. 4, by Ordway.

Hickory,  Carya sp. 
Noted July 29 and 30, by Clark and Ordway.

Honeylocust, Gleditsia triancanthos L. 
Noted Sept. 4 by Ordway

Kentucky coffetree / Coffee nut, Gymnocladus dioica (L.) 
Noted July 30 and Sept. 4, by Clark and Ordway.

Maple,  Acer sp.  
Noted Sept. 4 by Ordway.  This is another case where it is not known what species it would have been.  Box Elder, a maple with non-typical leaves but with the typical ‘whirley-bird’ seeds, was not mentioned until a long time later.

Mulberry, Morus rubra, Red Mulberry. 
Noted July 17 – July 30, by Clark and Ordway.  Red Mulberry is the native tree; the black, white, and paper mulberry are introduced species.  Mulberries have variable leaf shapes, but are readily identified.  In Missouri, the expedition found the berries ripe June 10th, and June 24th Clark commented on observing a great amount of bear signs “where they had passed in all directions through the bottoms in search of Mulberries, which were in great numbers in all the bottoms through which our party passed.”  However, they saw neither black bears nor bear signs in the Nebraska area.  In Omaha, Mulberries may start ripening around the 4th of July.  Incidentally, the Clark family home at Louisvillle, Kentucky, was called Mulberry Hill.

Oak,  Quercus sp. 
Oak was named 12 times, July 17 – Sep. 4, by four of the journal writers: Clark, Gass, Ordway, and Whitehouse.  White Oak was specified two of those times.  The leaf tips of the Red Oak are pointed. Curiously, the expedition seems not have seen the Bur Oak until later, Sept. 16 in South Dakota, when Lewis described it in detail and noted that “almost every species of wild game is fond of the acorn”;  it was new to them so its leaves were collected and are in the Lewis and Clark Herbarium.  The Oak is the state tree of Iowa.

Red Cedar / Cedar,  Juniporus virginiana L., Eastern Red Cedar. 
Noted several times beginning Aug. 12th, by Clark, Gass, and Ordway.  Often on bluffs, being drier land.

Sycamore,  Platanus occidentalis L., American Sycamore. 
Noted July 18 and 30, by Clark.

Wahoo / Arrowwood, Euonymus atropurpureus, Eastern Wahoo. 
Arrowood was noted only one time, Sept. 4, by Ordway.  While several species of Viburnum are called arrowwood “having straight, tough stems formerly used by certain Native American peoples to  make arrows” as defined in the American Heritage Dictionary, Wahoo is also called Arrow-wood, Indian Arrow, or Spindle Tree.  Wahoo seems to be more widespread in this area than viburnums.  We grow the dwarf variety in our yards and call it Burning Bush.

Walnut / Black Walnut, Juglens nigra L., Black Walnut. 
Walnut was noted five times, July 17 – 30, by Clark and Ordway; it was called Black Walnut two of those times.

Willow, Salix sp.  
Willow islands, and willows along the river, were noted many times, one of the most common  features of the journey through many states.  On an island opposite the Nemaha River on July 11th, Clark described two small willows evidently new to them, one narrow and the other a broad leaf, evidently the Sandbar or Coyote Willow and the Peach-leaved Willow.  Both were described, or subspecies of them, much later when they were in Washington state, and Cutright considered them new to science.  Incidentally, they would have already been familiar with the Black Willow which grows in our area.

(Clark - July 18,1804) Little timber is to be seen except in the low points, on islands and on creeks.  The growth of timber is generally cottonwood, mulberry, elm, sycamore, etc.

(Sgt. Ordway - July 22, 1804, White Catfish Camp)  We set out early to find some good timbered land and a good place to encamp &12 miles from Great River Platte.  Camped&on the N. side [the north, or right side, to Ordway] of the Missouri.  We cleared away the willows and pitched our tents and built boweries.    (Clark)  Formed a camp on the S.S. [starboard or right side, to Clark] above a small willow island, and opposite the first hill which approaches the river on the L.S. [larboard or left side, to Clark] and covered with timbers of Oak, Walnut, Elm, etc.

(Ordway - July 29, 1804)  The Missouri is much more crooked since we passed the Great River Platte than before. & More praries, the timber scarser&the timber mostly cottonwood except on the hills, which is oak, black walnut, hickory, elm, basswood. & Camped on the north side [Iowa side] in a thin grove of cottonwood.

(Clark - July 30, 1804, Camp Council Bluffs, considered to be at Fort Atkinson) Each bend of the river forming a point which contains tall timber, principally willow, cottonwood, some mulberry, elm, sycamore and ash.  The groves contain walnut, coffeenut and oak in addition, and hickory and lynn.  (Ordway) We camped&close under the foot of the bluffs in a strip of woods which make along under the ridge to the river.  The timber is coffeenut, white oak, black walnut, elm, basswood or lynn, hickory, etc.  Below this is handsome bottom prairie; above the timber and bluffs is a beautiful high prairie.

(Ordway - August 22, 1804)  The hills make to the river on S.S. [south, or left side, to Ordway]. Below the hills there is some large timber of cottonwood, elm, maple, etc.  Some oak and cedar on the bluffs.  

(Clark - August 28, 1804, Camp Calumet Bluff, NE)  We came to below the Calumet Bluff and formed a camp in a beautiful plain near the foot of the high land. & Our camp was in a wide bottom, in which were large elm and oak trees.

(Ordway - September 4, 1804, the day they passed the Niobrara River)  Found some plums and hackberries. etc. & Passed a handsome bottom covered with different kinds of timber such as red ceder, honey locust, oak, arrowood, elm, coffeenut, etc.  We camped on the South Side in a cedar bottom back of which are steep cliffs covered with cedar.