Angiosperms

Introduction to the Structure of Flowering Plants

What is an Angiosperm?

• In Division Anthophyta; can be trees, shrubs, herbs, vines, etc., and found in all environments

• Have seeds, roots, stems, and leaves• Produces flowers (specialized leaves)• Produces seeds in a fruit, either fleshy or dry• Divided into 2 classes, monocots (1 seed leaf) and

dicots (2 seed leaves)• Have sophisticated environmental adaptations

Angiosperm Organs

• Roots• Stems• Leaves • Flowers• Seeds

Roots

• Underground parts• Anchor the plant• Absorbs water/minerals• Transports solutions up• Stores nutrient starches;

several edible• Thin/thick; short/long;

singular/branching

Cross section structure• Epidermis with root hairs• Outer cortex for

transport/storage; some of it is parenchyma

• Waterproof endodermis around vascular cylinder

• Pericycle producing lateral roots

• Vascular cylinder of xylem, vascular cambium and phloem

                 

    

Secondary root emerging from the pericycle

Xylem transports water and dissolved minerals up and outward to the rest of the plant

Phloem transports the products of photosynthesis, like glucose, down and out to the rest of the plant

Vascular tissues:

Stems

• Aboveground parts• Support and display

leaves and flowers• Transport through

many vascular tissues• Stores some starches• Produces leaf and

flower buds by way of apical and lateral meristems

Herbaceous – soft and green as in small herbs and some shrubs

Woody – firm as in shrubs and trees (old xylem provides our

firewood from trees)

Stem types

Cross-section structure (herbaceous)• Vascular bundles of

mixed xylem/phloem• Surrounded by cortex of

parenchyma tissue• Vascular bundles

scattered in monocots• Bundles in an outer ring

in dicots• Epidermis outside;

endodermis surrounding bundles

Dicot?

Cross-section structure (woody)

• Cork (bark) outside• Cork cambium

produces cork• Phloem layer• Vascular cambium

makes phloem outside/xylem inside

• Rings of annual growth of xylem

Leaves

• Waxy cuticle on top• Upper epidermis layer• Palisades parenchyma

loaded with chlorophyll• Spongy mesophyll with air

gaps and veins of vascular tissue (gas exchange)

• Lower epidermis with numerous stoma

• Waxy cuticle underneath

Actual photomicrograph of leaf XS

Flowers• Sepals from bud cover• Colorful petals protect

interior structures• Stamens of filaments and

pollen-laden anthers• Pistil(s) with sticky stigma,

long style, and egg-making ovary at the base

• All attached to a long peduncle

• May have all parts or a mixture of parts

The pollen, or male gametophyte (gamete-producing plant ) and the ovule, or female gametophyte,

represent the sexual generation in the life-cycle of the flowering plant. The pollen may be transferred to the stigma of the same flower or to the stigma of another

flower of the same species. In the former case the process is called self-pollination, in the latter case,

cross-pollination.

Pollination

FertilizationOn the stigma, the pollen germinates, and produces the male gametes which are transported to the ovule in a pollen tube. One of these male gametes fuses with the female gamete within the ovule. This fusion, called fertilization, marks the beginning of the development of the embryo plant. The tissues of the ovule surrounding the embryo form the seed, while the tissues of the ovary, sometimes with some of the surrounding structures, form the fruit. The fruit is the ripened ovary (ovaries) with the enclosed seeds, if any, and in some cases may include other parts of the parent flower. The characteristics of the fruit are thus closely related to the characteristic of the flower (or flowers), and especially the ovary (or ovaries) from which it was produced.

Review (write down responses) • The plants most familiar to you, including fruit

trees, vegetables, cereal grains, and wildflowers are ____________________

• Angiosperms and gymnosperms are alike in that they both have _________, _________, __________, and _____________.

• Angiosperms produce __________ and have their seeds in ___________.

• Flowering plants are in the division ____________• The 2 classes of anthophytes are ______________

and ___________________.

• Grasses, orchids and lilies have 1 seed leaf and are called _________________; _____________ have 2 seed leaves.

• One advantage to plants having fruit-covered seeds is added protection for the _____________.

• Water and minerals enter the root by absorption into the ____________________.

• The size of the stomata is controlled by the ________ cells.

• Most photosynthesis occurs in the __________

____________.

• Transfer of pollen from the anther of one flower to the pistil of another is called ____________ pollination.

• The outermost structure on a flower is the ______________.

• Egg cells are produced in the __________ of the pistil.

• The seeds, and therefore the embryo, are protected by a structure called a _____________, either fleshy or dry.

• The primary function of ____________ is to trap light energy for photosynthesis.

• Roots, stems, and leaves all function as ________

• Cambium and apical meristem are examples of ___________ tissue.

• The plant anchor is the ____________.

• The plant’s version of water, sewer, and gas utilities would be the ____________ tissues.

• Plant food is transported in ____________ tissue.

• Water and dissolved minerals are transported in ___________ tissue.