70 MISSOURI BOTANICAL GARDEN. 
plant forms along the margin of an ox-bow lake; Nelumbo lutea, 
Jussiaca repens, Scirpus maritimus, Salix nigra and S. amygdaloides. — 
Horse-Shoe Lake. 
Plate 9.—1, Zone of Scirpus maritimus with Polygonum Muhlendergii 
behind it, Populus monilifera and Salix nigra on the left, Betula lutea in 
the center, and Salix amygdaloides on the right. —Horse-Shoe Lake. 
2, Margin of small stream which enters Horse-Shoe Lake. In the fore- 
ground is Jussiaea repens, in the middle ground, Polygonum Muhlenbergii 
and Sium cicutaefolium, and in the background a thicket of Salix nigra, S. 
amygdaloides and S. longifolia which merges into a dense thicket of 
Forestiera acuminata, the interior of which is shown in the next figure. 
Plate 10,— 1, Thicket of Forestiera acuminata which spreads rapidly 
by vegetative propagation. Large tree in the foreground is Salix nigra. 
2, Forestiera acuminata, showing common method of vegetative propaga- 
tion. — Margin of Canteen Creek, near Horse-Shoe Lake. 
Plate 11.—1, Willow swamp along Canteen Creek, with Forestiera 
acuminata, Cephalanthus occidentalis, Polygonum Muhlenbergii, Mentha 
piperita and Sagittaria variabilis. 2, Polygonum-Zizaniopsis association 
in the St. Francis River, near Bertig, Arkansas. 
Plate 12.— 1, Open water zone, Varner River, bordered by growth of 
Nuphar advena and Azolla Caroliniana. —Near Kennett, Missouri. 2. 
General view of cypress swamp in the Saint Francis River, near Kennett, 
‘Missouri. 
Plate 13.—1, Channel of Varner River bordered by growth of Poly- 
gonum densiflorum. 2, Nuphar advena, Nymphaea odorata and Nelumbo 
dutea, along the Varner River. 
Plate 14.—1, Polygonum densijflorum, Typha latifolia, Saururus cernuus 
and Peltandra undulata, cypress, button-bush and willow undergrowth.— 
Varner River, near Kennett, Missouri. 2, Mixed cypress and tupelo 
forest along the Saint Francis River: Nuphar advena and Azolla Caro- 
liniana in the foreground. ~ 
Plate 15.— Group of young cypress trees, Taxodium distichum, growing 
in the water and showing enlarged base. 
Plate 16.— 1, Medium sized cypress with group of “ knees ”’ projecting 
nearly four feet above the water which is 30 inches deep at this point. 
2, Group of cypress trees in mesophytic condition; no knees or enlarged 
base. 
Plate 17.—1, Large cypress trees, 6 feet in diameter, surrounded by 
knees; the bases of these trees not enlarged. 2, Cypress with much en- 
larged base, surrounded by great number of knees, some of which are 
eight feet in height. — Margin of Saint Francis River, when usual waters 
have subsided. 
Plate 18, — 1, Large cypress surrounded by knees. 2 » Group of large 
tupelo, Nyssa uniflora, showing characteristic enlargement of base. The 
surrounding undergrowth consists of tupelo, button-bush, Aralia spinosa 
and Mikania scandens, 
