Characteristics of seed plants:
1. they have roots, stems , leaves, and vascular tissue
a. leaves – carry out photosynthesis
i. structures/layers of a leaf:
1. cuticle – waxy layer to reduce water loss
2. epidermis – upper and lower
lower epidermis has:
a) stomatas (stoma) – openings which allow the
exchange of carbon dioxide into the leaf and
oxygen out of the leaf
b) guard cells – special cells that “guard” the
opening; they open and close controlling the
rate of gas exchange
3. palisade (mesophyll = middle layer) – just under upper
epidermis; long, narrow, and tightly-packed cells with a lot of
chloroplasts – where the majority of photosynthesis occurs
4. spongy layer – just under palisade layer; loosely arranged layer
with a lot of air spaces; gas exchange for photosynthesis;
contains vascular tissue
b. stems – usually above ground; supports branches; contains vascular tissue;
storage site of photosynthetic products
i. herbaceous – green stems; photosynthetic
ii. woody – non-photosynthetic
c. roots – supports/anchors the plant; storage site of sugars/starches produced in
leaves by photosynthesis; absorbs water and nutrients from soil
i. fibrous root system – many roots from bottom of stem
ii. tap root system – one main root; example – carrot
d. vascular tissue – usually in bundles/grouped together
i. xylem – carries water throughout the plant in hollow, stacked, tubular
cells called tracheids
1. in flowering plants – there are also vessel elements = additional
xylem tubes with larger openings
2. pits in tubes allow water to move freely up the roots and stems
to leaves
ii. phloem – carries dissolved sugars (products of photosynthesis)
throughout the plant in similar system of tubular cells
1. companion cell – help to control the function of sieve-tube
2. sieve-tube element
iii. cambium – specialized cells responsible for producing new xylem
and/or phloem for the growing tree; just under the outer/bark layer of
the plant
2. produce seeds which contain an embryo (young plant) and stored food for the
developing plant
3. 2 major divisions:
a. gymnosperms – oldest trees alive
i. seeds are in cones
ii. do not have flowers
iii. referred to as evergreens
iv. important in lumber and paper industry
v. resin/sap is important in paints, perfumes, and medicine
vi. needle-like or scale-like leaves
vii. 4 groups:
1. conifers – pine trees, redwoods, firs, spruces, junipers
a. woodlands
b. separate male and female cones
c. both are on the same plant
d. male cones higher on the plant; produce pollen to
fall by gravity to female cones below
2. cycads – palms; tropical zones
3. gingkoes
4. joint firs
b. angiosperms – flowering plants that produce fruit with one or more seeds; fruit
develops from the flower; most economically important plant group on earth
(clothing, rubber, perfumes, medicines, flavorings, dyes)
2 divisions:
i. monocotyledons or monocots - one cotyledon/seed storage
a. flowers are in multiples of three
b. leaves are narrow with parallel veins/vascular tissue
c. vascular bundles are scattered throughout the stem
d. examples: corn, rice, wheat, barley, bananas,
daisies, lilies
ii. dicotyledons or dicots – 2 cotyledons
a. flowers in multiples of 4 or 5
b. leaves have branched vascular tissue/veins
c. vascular bundles are arranged in rings in the stem
d. examples: most shade trees (oak, maple, elm),
peanuts, apples, oranges
life cycle (from seed to mature plant) of angiosperms varies:
a. annuals – life cycle is complete in one year
b. biennials – life cycle takes 2 years; flowers and seeds occur in second year
c. perennials – life cycle takes more than 2 years; herbaceous or woody plants;
i. herbaceous – will appear to die in winter but return in spring
ii. woody – survive many years; most fruit trees