Like all plants, herbs are either annuals (basil, borage, calendula, and summer savory, for example) or perennials (such as anise hyssop, mint, and sweet woodruff). Some are biennials, which means they live for two growing seasons. (Click here for more on perennials and click here to look at annuals and biennials) A basic understanding of botany helps you grow happier, healthier plants. Much of the information in the following sections applies to all plants, not just herbs. However, we look at each item specifically with herbs in mind.

The Root Of The Matter

Herb roots are as important as the plant parts you see aboveground. Most herbs have either fibrous roots or a taproot:

• Fibrous roots are fine and highly branched. Herbs with fibrous roots are more susceptible to droughts because these roots grow closer to the soil surface. Plants with fibrous roots are easier to transplant and divide.
• Taproots are long and tapering with a few small side roots, or hairs. Usually thick and fleshy, taproots store moisture and stretch deep into the soil. Plants with taproots can withstand temporary droughts, but they’re less easy to transplant and can’t be divided.

Stem Dandy

Stems hold up the leaves and flowers, carrying water and nutrients to them from the roots. Only a few herbs - flax is one - are grown primarily for their stems, although you use the stems of many species in cooking and medicines.

Sometimes you’re told to cut below or above a node, the places along a stem where leaves are attached. The clear spaces between nodes are called internodes; without enough light, the internodes stretch more than usual, producing tall, spindly, leggy plants. Erect plants grow upward. Some shoot straight up, rigidly vertical and often with few side stems, such as bee balm. Others with more branched stems tend to sprawl. Climbing (or scandent) plants want to grow even farther upward.

Leaf It Be

Anyone with an herb garden ends up being keen about leaves, as many of the most popular herbs have only small flowers. Herb leaves come in all sorts of sizes, colors, textures, and shapes. Each leaf variation (and there are scores) has its own name, but you can grow bee balm successfully for 50 years without knowing that its leaves are “simple, usually serrate,” or have great luck with geraniums without calling their leaves “alternate, palmate or pinnate, simple or compound, usually lobed.”

Following are a few of the most general leaf terms:

• Deciduous: Plants with leaves that die in winter and are replaced by new leaves in spring
• Evergreen: An everyday term for plants that retain leaves throughout the year
• Simple: A single leaf, like mint’s
• Compound: A leaf that’s made of several leaves, or leaflets, such as chervil’s
• Blade: The flat part of the leaf
• Margin: The leaf’s edge
• Lobed: A leaf, like most geraniums’, that has deep cuts
• Serration: Leaf margins that are jagged, like most mints’ (A leaf without serration, such as that of orrisroot, has entire margins.)

Flower Children

Gardeners describe flowers both in terms of the individual blooms and the way those blooms are arranged. Knowing the basic terms for these inflorescences (flower clusters) helps you to choose the flower shape you want. And when other gardeners start talking blossoms, it won’t be all Greek to you.

• Composite: A daisylike flower, such as the sunflower, that looks like a single (one flower on one stalk), but actually consists of a center made up of scores of tiny, tightly packed disc flowers surrounded by a ring of ray flowers (the flower parts we pick off while reciting, “He loves me, He loves me not”).
• Panicle: An open, loosely branched cluster of flowers on a branched stem.  ....read more