Study Set Content:
Modifications develop in the mesophyll
Conspicuous resin canals
is aromatic and antiseptic and prevents the development of fungi; it also deters insect attacks. Other conifers apparently produce resin canals in response to injury.
Resin
are formed both vertically and horizontally throughout various tissues
Resin canals
Pines Companion cells are absent from the phloem, but similar (blank)apparently perform the same function.
albuminous cells
have the appearance of a cross between a tree fern and a palm but are related to neither
Cycads
slow-growing plants of the tropics and subtropics have unbranched trunks that grow more than 15 meters (50 feet) tall in a few species and have a crown of large, pinnately divided leaves.
Cycads
number of known living species of cycads are presently facing extinction.
240
During the Mesozoic era, now-extinct gymnosperms known as (blank) were abundant
cycadeoids
bore a superficial resemblance to cycads but had very different reproductive structures and are not related
Cycadeoids
10,000 to 20,000 spirally arranged flagella.
sperm of cycads
Cycads are
dioecious
name is derived from Chinese words meaning "silver apricot”
Ginkgo
family of Ginkgo
Ginkgoaceae
are often referred to as maidenhair trees because their notched, broad, fan-shaped leaves look like larger versions of the individual pinnae of maidenhair ferns.
Ginkgoes
They are deciduous and turn a bright golden yellow before abscission in the fall.
Division Gingkophyta
They are widely cultivated in the United States and are popular street trees in some areas.
Division Gingkophyta
number of known species of gnetophytes are distributed among three distinctive genera
100
They are unique among the gymnosperms in having vessels in the xylem.
Division Gnetophyta
More than half of the gnetophytes are species of joint firs in the genus
Ephedra
Division Gnetophyta nhabit drier regions of
southwestern North America
