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Randa, Bio103
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Chapter 30
The Plant Kingdom: Seed Plants
I. Gymnosperms: “Naked Seed” Plants
A. Gymnosperms include some of the largest plants, the tallest plants, and the oldest trees.
1. may be classified into 4 Phyla
2. largest = Phylum Coniferophyta
3. Phyla Ginkgophyta and Cycadophyta are remnants of once successful groups
4. Phylum Gnetophyta is an odd group
B. Conifers -- Phylum Coniferophyta
1. conifers include pines, spruces, and firs
a. are woody trees or shrubs: typically do not have deciduous leaves (needles)
b. most are monoecious , bearing both male and female cones on the same tree
c. dominate in cooler areas of the northern hemisphere, and some areas of S. America,
Australia, and Malaysia
2. pines represent a typical conifer life cycle
a. pine tree = sporophyte; produces microspores and megaspores
b. male cones have microsporophylls with microsporangia which contain
microsporocytes
i. microsporocytes → haploid male gametophyte (pollen grain)
ii. pollen grains wind dispersed
c. female cones larger than the male cones
d. female cone opens at the time of pollen release
e. pollen grains grow through a pollen tube that grows into the female gametophyte
f. tissue of the female gametophyte becomes nutritive tissue in the mature seed
i. seed coat surrounds the embryo and nutritive tissue
ii. a papery wing develops to allow wind dispersal
C. Cycads -- Phylum Cycadophyta
1. only ca. 100 spp. of cycads remain
2. restricted to the tropics and subtropics
3. leaves of cycads resemble the leaves of ferns or palms
D. Gingkoes -- Phylum Ginkgophyta
1. represented by a single extant species Ginkgo biloba
2. extinct in the wild
3. commonly planted in cities, as they are resistant to air pollution
4. seeds from female trees are very odorous
E. Gnetophytes: Phylum Gnetophyta
-- has 70 spp. within only 3 genera, Gnetum, Ephedra, and Welwitschia
Randa, Bio103
II. Flowering Plants -- Phylum Anthophyta
A. Produce flowers, fruits, and seeds
1. ubiquitous and very speciose
2. flowers = the organ of sexual reproduction; seeds develop within a fruit
3. angiosperms have efficient conducting tissues
4. all of our major food plants are angiosperms
B. Two groups of flowering plants -- monocots and dicots
1. Clade [Class] Monocotyledones
a. typically herbaceous
b. e.g.: lilies, grasses, corn, palms, and orchids
c. parallel leaf venation
d. floral parts in multiples of 3
e. fibrous root system
f. scattered vascular bundles
g. 1 cotyledon in the seed
2. Clade Eudicot [and other Dicots; formerly Class Dicotyledones]
a. may be herbaceous or woody
b. e.g.s: roses, oak trees, potatoes, and daisies
c. netted leaf venation
d. floral parts in multiples of 4 or 5
e. tap root system
f. vascular bundles arranged in a ring
g. 2 cotyledons in the seed
C. Sexual reproduction
1. flower parts: sepals, petals, stamens , and carpels
a. sepals and petals = sterile modified leaves
b. stamens and carpels = fertile modified leaves
c. flower with all four parts = complete
if missing any part = incomplete
d. flower with both stamens and carpels = perfect
if has only stamens or only carpels = imperfect
2. sepals protect other flower parts while it is in bud
3. petals are typically brightly colored;
collectively referred to as the corolla
4. stamens: filament and anther
5. carpels = female reproductive organs
6. the female portion of the flower: pistil
--each pistil has a stigma, a style, and an ovary
--ovary contains ovule/s
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Randa, Bio103
D. Double fertilization
1. 1st fertilization: union of egg and 1st sperm → embryo
2. 2nd fertilization: union of polar nuclei and 2nd sperm → endosperm
seed: develops from ovule
monocots-- endosperm persists in the mature seed
dicots-- endosperm is absent in the mature seed
fruit: enlargement of ovary around developing seed/s
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