By Clayton Smith

Plants are organic beings living in the midst of their created world. It is only through organized chaos that their appearance comes into being.

In this article we are going to look very hard and long at the structure of plants.

All plants by their very nature, and with very few exceptions, have 3 basic parts:
1. Leaves
2. Trunks, stems and branches
3. Roots

Some would classify flowers as another part of the plant but, as any plant physiologist or botanist will tell you, flowers are just a form of modified leaves. However, ironically, it is by flower morphology that we actually divide and classify plants species. Leaf morphology is sometimes used but is very inaccurate when it comes to keying down to species.

Think of plants as factories. The roots would be the storage warehouse where raw goods come in and finished goods are stored. Stems and branches are the factory transport - forklift and conveyer belts with housing added on. The leaves are the processing and manufacturing areas, where the raw material is taken in and converted, by photosynthesis, to usable and stored energy.

Roots have 3 basic parts:
1. Epidermis
2. Cortex
3. Vascular cylinder, which contains the xylem and phloem tissues (we will look at closely at this in the stem structure of the plan).

The epidermis of the root is where the root hairs are found and raw materials and water and taken in, by a process called osmosis. Osmosis is the process whereby the concentrating of water and certain raw essential minerals is higher than the root hairs, which have a lower concentration of these minerals. Membranes in the root hairs allow these minerals to pass roots cells, called vacuoles, where the pressure differentiation is lower than in the surrounding cells, thus allowing movement. The rate of diffusion of the raw material into the root hairs is proportionally equal to the concentration of the raw material outside the root hairs. Plants have no choice but to take in these raw materials and water if the concentration is higher outside the root zone. That is why we can have fertilizer burn and overwatering of plants. They have no choice.

The cortex is the greatest area of the roots and that is where starch, sugars and other substances are stored. Think of a carrot. Most of it is sugars and starches, wrapped in a protective layer of epidermis cells.

Speaking of carrots, roots are also divided into two types: branching and taproots. Corn has branching roots whereas carrots have tap roots. Most of the active root hairs can be found in the upper 3 feet of the soil, and the remainder of the root is used as a foundation to hold up the plant.

The vascular cylinder of the roots is where the water and the raw and finished materials are moved throughout the roots. The xylem tissues move the materials up to the stem and branches while the phloem tissues move the finished products back down to the cortex or storage tissues.

The stems and branches, as mentioned above, are the transportation and structural housing of the plant. For most dicots the trunk and stems have five basic parts. The first is the bark, which is the protective coat and has both an outer and inner layer. The main purpose of the bark is protection from insects, diseases and the environment (for example, fire). It also keeps the moisture in and keeps the plants from drying out. Inside the bark is the second layer, called the phloem layer. The phloem layer in the trunk, as in the roots, moves the finished material from photosynthesis in the leaves back down the plant to storage cells in the cortex of the roots. There are different types of cells found in the phloem that each have their own job of moving the energy back down.

In between the phloem tissues and the fourth layer, the xylem, is the cambium layer. This is a layer of undifferentiated cells that produce both the phloem and xylem layers on one side and the other. To define the cambium layer a little bit more, we must realize that there are only three growing points on a plant.

The first is the root meristem, the second is the apical meristem and the third is the cambium layer. It is from these tissues that all other plant cells are derived. It is also from these cells that plant tissue culture is done - that is because these cells are undifferentiated and can, through chemical means, be forced to differentiate into other cells. Both the root meristem and apical meristem can be found at the tips, while the cambium layer circumvents the entire trunk or branch.

The next layer after the cambium layer is the xylem layer, made up of tubes that - through capillary action - take water and minerals up to the leaves to be processed into energy. Like phloem tissues, the xylem layer has a number of different types of cells each doing a different job. It is from these cells that the rings found in plant trunks are formed. In monocots these layers of phloem, cambium and xylem are in bundles nestled inside the bark. These bundles are most noticeable in corn and sugarcane.

These phloem and xylem layers can be anywhere from a single cell thickness to multiple cell thickness, depending on the plant types.

The last and fifth layer is the pith, where the heartwood of trees is found. The pith layer is made up of dead xylem cells filled with various chemicals such as resins, oils, and tannic gums.

Another set of structures found in some plants along the stems and trunks is resin ducts. These are tube-like structures that contain resins and tannic gums and are used mostly as a protection against plant insects. For instance, if a burrowing insect encounters one of these tubes the insect will die, stuck to the resin. Insects many of millions of years old have been found stuck in these resin ducts, then fossilized into what we know today as amber. If you see a tree that is secreting resins it is most likely being attacked by insects.

The last structure of the plant is the leaf, where the majority of the raw material, taken up by the roots and transported by the trunk, is made into energy. Here is where most of the photosynthetic cells are found. That is not to say all of the photosynthetic cells are found in the leaves: there are many plants like the Desert Willow tree (Chilopsis linearis) and the Ocotillo plants (Fouquieria splendens) that have photosynthetic cells along their trunks and branches.

The leaf has 3 main layers:
1. The cuticle or upper and lower epidermis, which is the top and bottom of the leaf.
2. The mesophyll layer, which consists of the palisade layer and spongy layer. It is here where most, if not all, of the photosynthesis takes place.
3. The vein, which bundles the xylem and phloem tubes.

The epidermis, which is the cells covering the leaves, can have a variety of textures and colors. Some will have a deep protective waxy coating while others have thick, dense cover hairs that not only protect the leaf from damaging sun in the summer time but also protect it from predators wanting to munch on its tenderness. Many leaves also have cells that contain toxins poisonous to animals, and even to other plants. Let’s take, for instance, eucalyptus trees. Did you ever notice that there are few plants that can grow under eucalyptus? One reason for this is that when it rains, tannic resins found within their leaves are washed off into the soils, making the soil toxic to other plants. This is a means for survival - keeping all of the nutrients solely for the eucalyptus tree. Cedar trees also exhibit this same trait.

In the mesophyll layer, where most of the photosynthesis takes place, there are large intercellular spaces that exchange gas through specialized cells found in the epidermis called stomata. The stomata open and close depending on temperature and light. Under the epidermis and found in the mesophyll layer is the palisade layer, which is made of column-shaped cells that are attached to the epidermis, which contains most of the chloroplast cells, in which photosynthesis takes place. This is where the fun begins and most of the action takes place. Tiny motors called chlorophyll take the raw minerals, mix them in a combustion chamber with gases brought in from the outside to the mesophyll area and - bam! - energy is created. Nothing on earth can match these marvelous little engines. It is in these chloroplast cells that chlorophyll is found. It is the interaction and exchange of gases found in the spaces between the palisade layer and the spongy layer that bump-starts the photosynthetic process.

In the vein, you will find in bundles wrapped within the spongy layer, both xylem and phloem cells transporting minerals to and nutrients from the leaf. Nutrients and energy transported through the phloem tubes are then distributed back down through the plant and any reserves are then saved in the cortex of the root, thus completing the circle.

The recent string of high temperatures has taken a toll on gardens and gardeners alike! The lush green leaves of weeks past now have a yellow, or worse, brown/crispy appearance.

Bringing healthy life back into the garden is pretty basic: Increase water, cut out the dead stuff and feed! Mid-summer feeding is essential for ensuring a healthy and productive garden. Roses, citrus and evergreens tend to suffer from iron and nitrogen deficiency this time of year but with the proper food plants will green up very quickly. A rangy pile of petunias can be cut back and fed and within a couple weeks will explode with color again! Most garden plants including buddleia, salvia, shrubs and assorted annuals will benefit from a trim, a good drink of H2O and food. Organic sources of food are always better as they not only give the soil the nutrients necessary for supporting plant life, they also add essential bacteria. Meal or liquid form may be used. Meal is slower release and longer lasting; liquid, giving a quick fix, will result in faster results but require a more frequent feeding schedule. Since organic solutions feed the soil rather than the plant there is no danger of chemical burn. Plants will feed themselves directly from the soil, as they need it. A little extra effort today will give you lasting results!

The newsletter gives us a chance to answer questions that might be interesting to our readers. If you have something you would like to know, just reply to this email.

Question: How should I go about drying herbs from my herb garden?

Dry herbs such as basil, parsley, and sage to store through winter by cutting 6 -to 12-inch long stems. Remove any dead or diseased leaves, and hang stems upside down in paper bags in a shaded, airy, cool location.

Question: How do I know when to harvest my onions, and do I need to do anything special before storing them for later use?

Answer: To harvest onions for storage, watch for when the tops begin to turn yellow and fall over. The bulbs should be in the two- to four-inch range. At that point you may wish to bend the foliage flat to the ground to speed up the maturing process. After about three weeks, or when the tops are totally dried up, dig them up. (Do not harvest when the soil is very wet, and be sure to harvest before the first frost.)

Harvest on a dry, sunny day and lay the onions out to dry for an hour or so in the sun. Brush off any excess soil, then cure them by placing them in a single layer in the shade for about ten days. If conditions are inappropriate for outdoor drying, you may have to spread them out on the floor indoors under a fan. Finally, clip off the tops about an inch from the bulb and store in a cool dry place. Storage onion varieties will keep from 4-12 months when properly dried and stored.

By Tamara Galbraith

I can tell you honestly that it was a great day in my professional life when the dress code no longer included any hint of pantyhose.

That day also provided a gardening revelation: several new (and slightly vengeful) ways of re-using nylons to my advantage. So, if you're going through a pantyhose rebellion (or still use them but have some old ones you would have thrown out) - consider these smart ways to make stockings work for you:

Use as plant ties. Pantyhose are soft and stretchy, and are perfect for tying up those floppy tomato plants or vining fruits and flowers. Simply cut into small strips and tie loosely where needed.

Use as slings. For example, melons grow better elevated off of the ground, when good air circulation and heat surround the entire fruit. For smaller melons, use a pantyhose "sling" to tie the fruit up and off of the soil.

Use as a barrier. For stem-chewing insects like cutworms and squash vine borers, a binding of pantyhose around the plant where the stem meets the soil can help prevent these munchers from getting access to the VIP lounge. The stocking will stretch as the plant grows.

Use as a strainer or "tea bag." If you're an organic gardener who likes to make your own "teas," i.e. alfalfa, compost, etc., the foot end of an old pair of pantyhose makes a great pouch for brewing gardening teas.

So, don't just throw your old stockings in the trash. Show those little nylon torture devices what "control" really is! (And remember, any leftover toe fluff can probably be considered organic....)