If you’ve flipped through a seed catalog recently, you’ve probably heard the cash register in your head buzzing away, adding figures fervently as you flip the pages. Falling in love with all those beautiful flowers and luscious vegetables gets costly quickly. You’ve probably been astounded when the final sum is revealed, weeding out the unnecessary and paring your list down to something that is somewhere between your dreams and reality.

‘Tis the season for ordering seeds, indeed, but let it also be the season for learning about saving seed. Raising your own seed can be simple, rewarding and fun. It can also help trim your seed expenses in spring, leaving more room in your budget for those that are hard to raise or difficult to harvest, treat and store.

Throughout history, saving and exchanging seed has been a tried and true method of dispersing horticultural crops and flowering ornamentals. At one time, before greenhouses and seed companies were common, seeds were valuable commodities. In fact, long ago in Europe, tulip seeds and bulbs were traded as currency. Some uncommon varieties were more valuable than gold. Today, harvesting your own seed is a way of ensuring the origin of your plants, securing your seed source and guaranteeing that your seed is chemical-free.

Before you start, it’s important to know a bit about how plants are organized taxonomically. The taxonomic system helps gardeners identify a particular plant with others to which it is related. The classification system follows this order: kingdom, phylum, class, order, family, genus, species, subspecies, cultivar.

We usually call plants by their common name, but if we were to refer to a plant using its botanical name, we would be using the taxonomic system to identify it. Botanical names generally include the plants’ genus, species and cultivar. Occasionally a subspecies name is used. If we were to refer to the tomato using its botanical name, we would call it Lycopersicon esculentum. Lycopersicon is the generic name; esculentum is the specific name. A cultivar would be Early Girl or Beef Steak.

For home-gardening purposes, seeds can be obtained only by crossing two parents of the same genus and species. For example, you can’t cross a sugar maple with a red maple. The botanical name for the sugar maple is Acer saccharum; the botanical name for the red maple is Acer rubrum.

Sugar maples can be crossed only with other sugar maples. Red maples can be crossed only with other red maples. Two cultivars of the same species could cross, resulting in offspring that may have qualities of both or neither parents.

The sort of open pollination that occurs between two plants of the same genus and species can produce seeds that yield plants similar to the parents, with some natural variation. However, seeds don’t always produce plants or fruits that look or taste like the plant they came from. Seeds contain a mixture of genetic traits from both the mother plant and the plant that pollinated the mother.

Cross-pollination can occur between two closely related plants. Broccoli and cauliflower can cross-pollinate, as can pumpkins and zucchini. The seeds that result from such cross-pollination often produce unusual looking fruits.

A hybrid is a plant that is produced by carefully crossing two selected parent plants to get a specific genetic combination. Hybrid seeds produce uniform plants, but don’t try to save seed from hybrids! The resulting seedlings show a broad range of inferior genetic traits.

If you are raising a patch of Brandywine tomatoes for seed, you’ll want to prevent the mother plants from cross-pollinating with other cultivars such as Beef Steak or Lemon Boy. Such a cross will produce seeds in the fruits of your Brandywine that will incorporate traits from the non-Brandywine cultivars.

In most cases if you want to maintain true varieties, it is necessary to prevent cross-pollination. To prevent cross-pollination between two plants you may:

1. Protect the flower buds as they emerge by covering them with a paper bag, cheesecloth or nylon stocking. This will minimize the chances of exposure to external pollen.

2. Hand-pollinate flowers as soon as they open with a Q-Tip, paintbrush, etc.

3. Select cultivars that bloom at different times in the season. This, too, will minimize the chances of exposure to related pollen.

Next week, I’ll share seven steps to successful seed saving. There are quick and easy techniques that will help you save seed from the most treasured garden vegetables to the most beautiful flowering annuals and perennials.

Diana George Chapin is the NEWS garden columnist. Send horticulture questions to Gardening Questions, RR1, Box 2120, Montville 04941, or e-mail them to dianagc@ctel.net. Selected questions will be answered in future columns. Include name, address and telephone number.