Botany:
Primitive Nonvascular Plants - Bryophytes
I. Features of the
A. Some traits are shared with the green algae, suggesting common ancestry
1.
2.
3.
4.
B. Other features of
1. Multicellular gametangia –
2. zygote (_______________________________________)
develops into an _____________________ within the tissues that
originally surrounded the egg.
3. Specialized tissues for photosynthesis, storage, conduction, etc.
4. Primarily _____________________ reproduction with dominant
_____________________ (spore-producing phase of the plant life
cycle) phase in more advanced members.
II. Our beginning of the survey of the
A. We will begin with the simplest of the true plants, the ___________________.
B. Note that these plants are nonvascular – they lack _____________________
& _____________________.
1. These plants are very small & cannot grow very tall because of the
problems of having no internal plumbing to move water.
III. Phylum _________________________________- liverworts.
A. The suffix wort simply means “________________” or “________________.” It was believed, incorrectly, that these plants (with liver-shaped lobes) were useful in the treatment of __________________________________________. The name stuck.
(image from https://goo.gl/images/uzd96w )
B. Structure and Form
1. Flattened, lobed bodies called _____________________.
a. Actually, only 20% of this division have the typical; liverwort
shape. The others look more like mosses.
2. Considered less complex than _____________________.
3. The _____________________ (gamete-producing phase of the plant
lifecycle) is the predominant generation, and makes up the thallus.
a. The thallus develops from a _____________________.
b. The lower surface is composed of small, single-celled, root-like
_____________________.
C. A typical liverwort is the genus Marchantia.
1. The Marchangia thallus is made up of air chambers with pores on the
top. Inside the chambers are loose chlorenchyma cells.
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Marchantia gemmae cups
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2. Asexual Reproduction: Marchantia reproduces asexually by _____________________—Lens-shaped groups of cells that are produced in gemmae cups, and are periodically released. (image from https://goo.gl/images/Uw5zJj ) |
3. Sexual Reproduction: Marchantia develop _____________________
that are more complex than most liverworts.
a. Male and female gametangia are produced on separate
gametophytes.
b. The gametangia are supported by gametophores called
__________________________________________ (females) and __________________________________________ (male).
Image
modified from the following source: http://www.dgsgardening.btinternet.co.uk/liverwrt.JPG
c. Archegonia containing _____________________ face
downward, while antheridia containing _____________________
face upward.
d. Raindrops splash the flagellated sperm away. The sperm swim
to an egg and fertilize it to form a _____________________.
e. The zygote divides to form an _____________________
(immature sporophyte).
f. The sporophyte is anchored to the archegonium, tucked up
under what looks like a palm tree.
g. Spores are formed by meiosis in the _____________________
of the sporophyte. The stalk of the archegoniophore will grow tall
so the resulting spores can be spread by the wind.
h. At maturity, the capsule splits and spores are carried by the
wind.
4. Other species of liverworts have bisexual gametophytes in which
antheridia and archegonia are produced on the same plant.
IV. Phylum __________________________________________- hornworts.
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A. Again, the suffix wort simply means “plant” or “herb.” Mature _____________________ often look like cattle horns, hence the name. (image from https://goo.gl/images/VdvWpp ) |
B. Gametophytes look similar to liverworts.
1. Most are very small, about 2 cm in diameter.
2. The pores and cavities are usually filled with _____________________
instead of air.
a. Nitrogen-fixing _____________________ often grow in the
mucilage. This relationship is mutualistic. The plant feeds the
bacteria sugar from photosynthesis and in return the bacteria take
nitrogen from the air and make fertilizer for the plant.
3. Usually hornworts have only one large _____________________ in
their cells. This is weird because higher plants have 75 to 125 chloroplasts
per cell.
4. _____________________ anchor plant to the surface.
C. Asexual Reproduction- usually by _____________________ - separation of
lobes from the thallus. (If the thallus (gametophyte) falls into pieces, each piece
become a new (genetically identical) gametophyte.)
D. Sexual Reproduction- archegonia and antheridia are usually produced on rows
beneath the upper surfaces of the gametophytes.
1. Gametophytes may be unisexual or bisexual.
2. Spores are produced throughout most of the hornlike sporophyte.
3. At maturity, the sporophyte splits, releasing spores.
V. Phylum __________________________________________- mosses.
**This is the most
important life cycle to know in this chapter! **
Image from:
MacMillian Higher Ed
A. The 15,000 species of bryophytes are divided into three classes…
1. _____________________ mosses – the most economically important
bryophyte.
a. Extremely _____________________ (more so than cotton) –
used to condition soils
b. Naturally _____________________ which inhibits bacterial &
fungal growth – has been used for _____________________
2. _____________________ mosses
3. _____________________ mosses.
B. Moss “leaves” have little or no tissue differentiation, and are haploid
(_____________________ is dominant).
1. The middle cells of moss “leaves” are non-photosynthetic and are
adapted to water accumulation and storage.
2. The axis is stem-like, but without conductive tissues.
a. Most water travels along the outside of the plant by
_____________________ and is absorbed by the plant surfaces.
C.
The plant is anchored by root-like rhizoids. Many
mosses have mycorrhizal
fungi associated with their rhizoids.
D. Mosses may have _____________________ and _____________________—
specialized cells that conduct water and food respectively.
1. These are not true vascular tissues and aren’t very efficient.
E. Sexual Reproduction- gametangia are produced from the gametophyte. Moss
species may be unisexual or bisexual.
1. The _____________________ produces a single egg cell.
2. The _____________________ produce numerous sperm cells that are
forced out of the antheridia when they absorb water and swell.
a. Each sperm has a pair of _____________________.
3. The archegonia release chemicals that attract the sperm.
a. Eventually, the sperm swim down the neck of an archegonium
and fertilize the egg to produce a _____________________.
4. The zygote grows into an embryo that remains attached to the
archegonium.
5. The sporophyte grows through the top of the archegonium and matures.
a. The developing sporophyte is covered by a pixie cap, the
_____________________.
b. The sporophyte is photosynthetic, but depends on the
gametophyte for some of its nutritional needs.
c. The sporophyte consists of a _____________________ that sits
on top of a stalk-like _____________________, which may be
very long in some species (15cm).
1) Spores are produced inside the capsule.
2) The free end of the capsule is usually protected by a
little rimmed lid, the _____________________, which falls
off at maturity.
3) Spores are released through the
_____________________.
6. The spores germinate to form strands called _____________________.
7. Small buds develop on the protonema that later develop into new
gametophytes.
F. Asexual Reproduction- Protonema may develop from most of the
gametophyte parts to form new gametophytes.
1. However, this is often done only under laboratory conditions.
2. The amount of asexual reproduction depends on the species.