Botany: Seed Plants - Gymnosperms

I. Gymnosperm- means “_______________________________”

A. The gymnosperms include all of the non-flowering seed plants.

1. Phylum _______________________________ – the conifers

(e.g. pines & others)

2. Phylum _______________________________ – Ginkgo trees

3. Phylum _______________________________ – the cycads

4. Phylum _______________________________ – the

gnetophytes

B. They are much more complex in their reproduction than the ferns

because they make seeds.

1. Still, they are less complex than the angiosperms (flowering

plants).

II. Characteristics of Gymnosperms

A. Seeds are referred to as “naked” because they are exposed on

_______________________________ instead of within fruits as in the

angiosperms.

B. Seed-bearing sporophylls are often arranged into strobili called

_______________________________.

C. A single plant usually produces both male and female cones (strobili).

1. Male strobili produce _______________________________

(immature male gametophytes).

2. The female gametophyte is produced within an

_______________________________ containing a fleshy, nutritive

_______________________________ that is enclosed within

several layers if diploid tissue called the ____________________.

D. Leaf forms

1. Palm-like – cycads

2. Needle-like – pines & firs

3. Scale-like – cypress & cedars

4. Broadleaved – ginkgo

5. Deciduous – larch & ginkgo

6. Evergreens – pines & cedars

III. Phylum (Division) _______________________________

A. This is the largest division of extant gymnosperms

1. Includes all conifers (e.g. the pines & others)

B. Characteristics

1. Usually, the fruits are dry woody cones, generally with several to

many scales

2. Stems are not jointed (as we will find in gnetophytes)

3. Leaves are either needle-like or overlapping & scale-like

C. Class Pinatae

1. The needles (leaves) are _______________________________

(clustered) in bundles of 2-5 needles/bundle.

a. When the needles of a cluster (fascicle) are held

together, they form a cylinder.

2. Most occur naturally throughout the Northern Hemisphere.

3. Pines often grow in harsh environments and have several

adaptations to them.

a. _______________________________- layers of thick-

walled cells below the epidermis

b. Thick cuticle and _______________________________

prevent water loss.

c. Resin canals- secrete and hold resin, deter fungi and

insects

d. Fascicles usually _______________________________

(fall off) every 2-5 years, but not all at the same time.

1) This is why we call them evergreens.

2) The advantage is that, during short growing

seasons, these plants do no have to waste time

growing leaves.

3) The cost is that they have to have leaves during

very cold & dry winters.

e. Xylem has no vessel elements, only

_______________________________.

1) Conifers are generally called

_______________________________.

f. Phloem has no companion cells, but instead have

_______________________________ cells that perform

the same function.

1) Remember that phloem cells have no nuclei at

maturity & must therefore be nursed by

neighboring (supportive) cells.

g. Most conifer roots have mycorrhizal fungi.

4. The _______________________________ of CA, NV, and UT

are among the oldest living organisms on earth (4600-4900

years).

a. In 1964, Donald R. Curry, a geologist from the University of North Carolina, was studying Ice Age glaciers by taking core samples in bristlecone pine. However, his corer broke and the U.S. Forest Service let him cut down Prometheus. Annual rings revealed that Prometheus was 4,844 years old. It was the oldest living thing on earth.

b. The next oldest tree, Methuselah, was dated to 4,789 years in 1957. It is still growing quietly in an undisclosed location, for its own protection.

**Be SURE to review the pine life cycle diagram in your book!**

D. Pine Reproduction

1. Microspores and megaspores are produced by

_______________________________

2. Every four microspores develop into a single

_______________________________ (immature gametophyte).

a. The pollen grains have wing-like air sacs that give them

buoyancy.

(Although pollen is often a culprit in allergies, pine pollen is

too large to be detected by the human immune system.)

3. Megaspores develop in the megasporangium surrounded by a

nutritive nucellus.

a. All but one of the megaspores deteriorates.

b. The remaining one develops into the ________________

_______________________________that consists of

around 1000 cells.

c. The gametophyte remains inside the nucellus, which has

a single opening called a ___________________________.

d. At maturity, 2-6 _______________________________

form at the end facing the micropyle.

1) Each archegonium contains a single

_______________.

e. Female cones usually take _______________________

to mature.

1) During the first year, the scales spread apart and

the micropyles secrete sticky drops (pollen drops)

that catch the ___________________________.

2) As the drop evaporates, the pollen is drawn down

into the nucellus through the micropyle.

3) After pollination, the scales grow together to

protect the developing ovule.

4) The megaspores do not develop until about a

month after ____________________________.

5) The female gametophyte does not mature for

another year.

4. Meanwhile, the pollen grain projects a _________________

_______________ that slowly digests its way through the nucellus.

a. Two of the four pollen cells enter the tube.

b. One cell (_______________________________) divides

to form a sterile cell and a __________________________.

c. The spermatogenous cell divides to produce 2 sperms.

5. _______________________________ after pollination, the

sperm tube reaches the archegonium.

a. One sperm fuses with an egg, the other cells disintegrate.

b. The sperms of other pollen grains may also fuse with

other eggs.

6. Each zygote develops into an __________________________.

a. As this occurs, one of the integument layers hardens to

become the _______________________________.

b. A membranous layer of the cone scale becomes a

_______________________________ on each seed.

E. Some conifers don’t produce woody cones.

1. Yews and California nutmeg produce

_______________________________ that look like cup-shaped

berries.

a. Yews have separate sexes of trees.

2. Podocarps (conifers of the Southern Hemisphere) produce

fleshy-coated seeds similar to yews, but are not open at one end.

3. Junipers have female cones that become fleshy at maturity,

giving them a berry-like appearance.

F. A survey of Class Pinatae- the conifers

1. Family Pinaceae – always have needle-like leaves & produce

cones with overlapping scales, each bearing 2 seeds.

Includes the following genera (plural for genus)…

a. Pinus – the pines are the largest genus of gymnosperms

with over 100 extant species.

1) Leaves fascicled in bundles of 1-5 needles per

bundle.

b. Abies – the firs

1) Needles not in bundles, rather they grow

separately on the stem.

c. Pseduotsuga – Douglas fir

1) Needles are separate & solitary

2) Very visible bracts occur between the cone scales

that look like mouse tails.

3) Branchlets are smooth.

d. Tsuga - hemlocks

1) Needles are separate & solitary

a) The leaves have short petioles.

2) Branchlets are roughened by persistent leaf bases

e. Picea – the spruces

1) Needles are separate & solitary

a) The leaves are sessile because they don’t

have petioles.

2) Branchlets are roughened by persistent leaf bases

2. Family _______________________________ – redwoods.

Includes...

a. Sequoia sempervirens (commonly known as the Coast

Redwood)

1) Needle-like leaves & small cone

2) _______________________________ (not

naturally found any other place in the world) to coastal

California.

a) Its specially shaped leaves harvest dew

from the ___________ that comes in from

the Pacific Ocean.

3) This tree is the __________________________

tree in the world. (approximately 350 feet tall)

b. Sequoiadendron gigantean (commonly known as the

Giant Sequoia or Big Tree)

1) Leaves are scale-like and clothe the entire branch

2) Cones are large in comparison to the Coast

Redwood.

3) Endemic to the southern Sierras of California

4) This species is the largest tree in the world in

terms of its ________________________of wood.

3. Family _______________________________

a. The leaves are scale-like and clothe the entire branch

b. Examples of this family are cypress, juniper, & cedar

4. Family Taxaceae

a. Characteristics

1) Needle-like leaves are separate & in flat sprays

2) Fruit is either solitary & berry-like or acorn-like &

one-seeded

b. Genera…

1) Taxus – yew

a) Berry-like fruit is red, edible, & very

palatable

b) Taxacol (cancer treating drug) is extracted

from its bark

2) Torreya – California Nutmeg

a) This is not the spice that nutmeg is taken

from

b) Has a one-seeded acorn-like fruit

c) Has solitary needles that are stiff with sharp

points.

IV. Phylum (Division) Ginkgophta – Ginkgo trees

A. Only extant species is Ginkgo biloba.

B. Often called “_______________________________” trees because its

fan-shaped, two-lobed leaves are shaped like maiden-hair fern fronds.

1. Leaves exhibit _______________________________ venation.

2. Broadleaf deciduous tree.

C. Geographic distribution

1. Native to the forests of remote western ____________________

2. Cultivated and grown around Chinese and Japanese temples

D. Trees are of separate sexes (_______________________________).

1. Male trees are nice to have around.  They only produce pollen.

2. Female trees produce a fruit that, when ripe, smells like rancid

butter or body odor.

V. Phylum (Division) Cycadophyta – the cycads

A. Most are extinct and the current 100 species or so are facing

extinction.

1. _______________________________ in appearance with large

central strobili

2. Tropical and subtropical

3. They grow slowly – a 6 foot specimen may be 1,000 years old

4. Dioecious

B. What makes them gymnosperms?

1. They produce cones (strobili) with seeds born on the cone

scales

2. Pollen cones (microsporangiate strobili)

3. Seed cones (megasporangiate strobili)

VI. Phylum (Division) Gnetophyta – the gnetophytes

A. Unique among gymnosperms in having _______________________

in the xylem.

B. Very diverse group of plants

1. More than half of all species are members of

_______________________________ (commonly known as the

joint firs or Mormon tea plant)—natural source of ephedrine.

a. Characteristics

1) Jointed stems

2) Leaves are small & scale-like in widely separated

whorls

3) Photosynthesis occurs in the stems

4) Cones are small & with thin scales

5) Desert-dwelling species

6) Looks like a dead shrub of straw-colored sticks

when seen from a distance.

b. Called Mormon tea because the Mormons used it to

make tea when they came west.

c. Ephedrine is a stimulant that was once used in

_______________________________ pills.

1) It was banned by the FDA because of an

association with _________________________.

2. Most of the remaining species are in Gnetum, which have broad

leaves like angiosperms. Most are tropical and vine-like.

3. _______________________________ has only one living

species and is found in the deserts of southwestern Africa. The

plant produces only two leaves during its __________________

lifetime. The leaves continually grow by meristems at the bases

and are split by the wind—giving the appearance of more

leaves.