HIGHER VASCULAR PLANTS - seed plants including; Cycadophyta, Coniferophyta, Angiospermophyta. These plants have a gametic life cycle in that the gametophyte never leaves the protection of the seed. The new sporophyte arising from the fertilized egg does so inside the seed and only 2n tissue ventures out to produce a new sporophyte plant with roots and shoots.

Phylum Cycadophyta - Cycads are the first group we have looked at with seeds. There are many species of seed ferns in the fossil record but none surviving. There are tree ferns, still living.

Seeds are a significant advance over the spore bearing plants. Spores (haploid) blow away from the plant and produce a microscopic haploid (gametophyte) thallus which produces antheridia and archegonia in the lower sporic vasculars (Psilophyta, Lycophyta, Sphenophyta, & Pterophyta).

Seeds enclose and nuture the developing female gametophyte in several layers of diploid [2n] protective tissue

Strobilus - cones. A megastrobilus (female cone) produces a multicellular haploid [1n] female gametophyte in elope two archegonia each protecting an egg.

A microstrobilus (male cone) produce microsporangia in which many multicellular haploid male gametophytes (pollen grains) are produced

Cycad leaves are large and often more finely dissected than ferns. They have a better epidermis and cuticle and withstand dry conditions somewhat better than ferns but still are mainly found in rainforest and tropical areas.

Cycads are perrenial growing a new set of leaves from the top of the short trunk.

Some older leaves when heavily shaded drop off. The plant grows slowly taller on a trunk of leaf basesfrom previous years, but there is no trowth, cambium or buds.

Microstrobilus (male cone)

Megastrobilus (female cone) of cycads
Male cones usually shorter lived produce pollen

Cycad Stem cross section - has a central pith of parenchyma cells, middle ring of vascular tissue (xylem & phloem), and an other ring of protective cortex cells.

Ther is no cambium, and little structural woody tissue

Picture 1 An unfertilized ovule inside each of two archegonia [2] inside a haploid multicellular female gametophyte [1] surrounded by diploid nucellus (seed coat)[3] and diploid integument[4]. Gametophyte is maintained in this protective environment through fertilization and early embryo formation

Image 2 Seed - mature hardened seed coat with multicellular embryo in dormant suspended growth state.

Image 1 Microsporangia cross section with pollen grains

Image 2 Megasporangia cross section with female gametophyte, archegonia, and egg (Zamia, cycad)

Image 1 Phylum Ginkgophyta Ginkgo cones

Image 2 male cycad cone
Phylum Coniferophyta - conifers or evergreens. These fossils from the mesozoic (200 million years ago) bear some resemblence to yews and also to some cycads.

Conifers are divided into these Families; Taxaceae - yew (most primitive)

Pinaceae - fir, spruce, hemlock, pine, larch

Cupressaceae - cyprus, cedar, juniper

Monopodal branching- all conifers have one main trunk with a whorl of branches at each years growth node. Multiple buds occur terminally only which limits growth potential

Conifer leaves - can be needles, scales, or more cycad leaf like
Conifer stems - have a clear cambium, secondary growth, strong woody structural support, resin ducts, ray fibers, corky bark
Conifer leaves (needles) much smaller surface to volume ratio,thick cuticle, and sunken stomata, to reduce water loss and expand the range into drier and colder habitat.
There are a great variety of cones among conifers but all are wind pollinated and seed desceminated. Some cones will not open to shed seeds unless there is a fire.
Female cone (megastrobilus) cross section showing protective sporophyll, megasporangia with ovules. Pollen must blow into the cleft open space grow through a small opening into the archegonia and female gametophyte. This openning is called the micropyll.
Megasporangia with micropyll, two archegonia, each with an egg in a multicellular haploid female gametophyte.
Microsporangia (male cones) appear in the spring of the year, shed pollen and deteriorate. Female woody cones may last on a tree several years.

Phylum Angiospermophyta - flowering plants. There are two main classes;

Dicotoledonae - have tap roots, net veined leaves, flower parts in 4's or 5's, and 2 cotyledons (seed leaves) in the seed.

Monocotyledonae - have fibrous roots, parallel veins, flower parts in 3's, and one cotyledon in the seed

Angiosperm root - has a root cap with stout lignified protective cells, that act like a plow [3], a region of meristematic activity [2], and a region of elongation [1] in which vascular tissue is darker stained

beyond the regions shown would be a region of differentiation where root hairs develop, and above that a region of maturation where root hairs give way to bark
Dicot root - cross section has a star shape group of zylem vessels for conducting water up the root. In the axials of the xylem is phloem (food conduction down). This is called the stele (actinostele) and is separated from the cortex by two cell layers. The inner layer [8] produced by the stele is the pericycle. The outer layer [9] produced by the cortex is the endodermis. Between them is laid down a waxy layer (casparian strip) that acts as a impermiable straw to prevent water being pumped up or drawn up from leaking into the cortex.
Most woody plants (trees and shrubs) branch polychotomously as opposed to monopodally. Buds are lateral as well as terminal. This allows for much more varied growth into lighted areas. Greater flexibility than the conifers.
Monocot stems -(attactosteles) have scattered vascular bundles throughout the cortex and pith. Xylem elements are nearer the center of the stem with phloem toward the exterior. These stems have no secondary growth. Most monocots are annual to perennial with growth each year from the roots or rhyzomes.
Dicot stems (Dictyostele) have vascular bundles in a concentric ring. Each bundle is divided into inner xylem and outer phloem by the light band of totipotent cells called the intrafacicular cambium. This expands across to adjacent bundles to form a complete cambium encircling the branch and allowing secondary growth of a 2nd years tissue. This type of vascular system occurs in dicot herbs and first year growth of woody dicots.
Angiosperm leaf whether dicot or monocot has an upper epidermis with waxy cuticle, a palasade parenchyma layer that is the main photosynthetic layer (long collumnar cells), spongy mesophyll layer which is the main water and starch storage area of the leaf, a lower epidermis and cuticle with frequent stomata with guard cells to control influx of air.
Dicot net veined leaf
Epidermal cells of a leaf (top view) with the smaller couplet cells (guard cells) which can open and close by osmotic pressure
Hypogynous flower - most primitive and most common. All flower parts arise from the receptacle under the ovary.

Perigynous flower - flower parts arise from a protective cup that rises halfway up around the ovary called the hypanthium

epigynous flower - hypanthium arise to the top of the ovary completely enclosing it. Flower parts arise off the top of the ovary.