Geoscience Reference
In-Depth Information
Figure 6-21.
Pickerel weed (
Pontederia cordata
). The
spade-shaped leaves and delicate violet l owers are
quite attractive, and pickerel weed is a popular
ornamental plant (see Color Plate 6-21). It may form
dense cover in shallow marsh, pond and lake
environments. Photo by J.S. Aber; Conneaut Marsh,
northwestern Pennsylvania, United States.
Figure 6-20.
Cattail (
Typha
sp.). The mature seed head
(spadix) is about to disperse a multitude of tiny
seed-bearing fruits (achenes) that are carried by
numerous long hairs in the wind. Cattail has a
tendency to become invasive, especially the hybrid
variety (
T. glauca
). Photo by J.S. Aber; Flint Hills,
east-central Kansas, United States.
“countless” (Greek:
myrios
) leaves (Latin:
phyllus
), which refers to its many, i nely divided
leaves (Fig. 6-26). The genus is widely spread
across North America, Greenland, and Eurasia.
Northern water milfoil is an important food and
shelter plant for i sh and invertebrates from
Alaska to Texas. However, Eurasian water milfoil
(
Myriophyllum spicatum
) has been introduced
in North America, where it is more competitive
than native species (Lahring 2003).
Bladderworts
(
Utricularia
sp.) - Several
species of largely underwater plants with some
l oating leaves (Fig. 6-27). The name comes from
small bladders for catching aquatic inverte-
brates. The lip of the bladder has hair triggers;
when touched the bladder springs open and
the prey is sucked inside and trapped. Enzymes
then dissolve the body, and nutrients are
absorbed into the plant. In this manner, the
6.2.4 Submerged plants
The submerged category has mostly underwater
plants with few l oating or emergent leaves.
Flowers may emerge briel y in some cases for
pollination, and some plants may have l oating
or aerial leaves that are quite different from
submerged leaves, as with many pondweeds.
Because these plants are largely submerged,
they are rarely seen by the general public and
are not readily photographed in nature. The
depth of such plants is limited by light penetra-
tion, which depends primarily on suspended
sediment (see section 6.1.1).
Northern water milfoil
(
Myriophyllum
sibiricum
) -
Myriophyllum
means “many” or
