Page 122 - Ultimate Visual Dictionary (DK)

PLANTS

Horsetails, clubmosses, CLUBMOSS
Lycopodium sp.

and ferns

HORSETAILS, CLUBMOSSES, AND FERNS are primitive land Stem with
spirally
plants, which, like higher plants, have stems, roots, and leaves,
arranged
and vascular systems that transport water, minerals, and food. leaves
However, unlike higher plants, they do not produce seeds when
Branch
reproducing. Their life-cycles involve two stages. In stage one,
the sporophyte (green plant) produces spores in sporangia.
In stage two, the spores germinate, developing into small,
short-lived gametophyte plants that produce male and female
gametes (sex cells); the gametes fuse to form a zygote from
which a new sporophyte plant develops. Horsetails (phylum
FROND
Male fern Sphenophyta) have erect, green stems with branches
(Dryopteris arranged in whorls; some stems are fertile and have a single
filix-mas)
spore-producing strobilus (group of sporangia) at the tip.
Clubmosses (phylum Lycopodophyta) typically have small leaves arranged
spirally around the stem, with spore-producing strobili at the tip of some
stems. Ferns (phylum Filicinophyta) typically Strobilus
CLUBMOSS (group of sporangia)
have large, pinnate fronds (leaves); Selaginella sp.
sporangia, grouped together in sori, Cortex (layer
Epidermis between epidermis
develop on the underside (outer layer and vascular tissue) Shoot
of fertile fronds. of cells) apex
Branch
Rhizophore
HORSETAIL Vascular Phloem (leafless
Common horsetail tissue branch)
(Equisetum arvense) Apex of Xylem
sterile shoot
Sporangiophore
(structure Lacuna
carrying (air space)
sporangia)
Creeping stem with
MICROGRAPH OF CROSS-SECTION spirally arranged
THROUGH CLUBMOSS STEM leaves
Strobilus
(group of
sporangia) Endodermis Vascular tissue
Lateral (inner layer Sclerenchyma
branch of cortex) (strengthening tissue)
Chlorenchyma
Photosynthetic Epidermis (photosynthetic
sterile stem (outer layer tissue)
Non-photosynthetic of cells)
fertile stem Node Parenchyma
(packing
Young Internode Cortex tissue)
shoot (layer between
Collar of small Tuber epidermis and Hollow pith
Node
brown leaves vascular tissue) cavity
Vallecular canal Carinal canal
(longitudinal channel) (longitudinal
channel)
Rhizome MICROGRAPH OF CROSS-SECTION
Adventitious root THROUGH HORSETAIL STEM

120