Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species: Whew! Well that's how living things are catagorized. We can assume that all of out plant-related interests can be dealt with by concentrating on just family, genus, and species.
Example: A ponderosa pine and a white pine both belong to the family Pinaceae, but so do the fir trees. In fact so do cedars and hemlocks. (There are others too, but we won't see them in our area.) The two pines are in the genus Pinus, but the fir is in the genus Abies. The ponderosa pine species is Pinus ponderosa, the white pine species is Pinus albicaulis. It is useful to know that there are several more “white pines” found across the United States, including an eastern white pine. What if you want to make sure I know you're talking about that one? You would simply mention Pinus strobus and I would easily look it up. Botanical names remove confusion. By the way, when discussing a list of plants, once the genus name has been mentioned it can be shortened to just the first letter for other mentions of the genus. Thus, Pinus ponderosa and P. albicaulis are both trees of the western Sierra Nevada.
First Major Tip
To key a plant, you are going to look at a series of questions that should only provide one good answer: Is the item black or white? You choose the answer that best fits and that leads you to the next question that relates only to that choice: Is it round or square? You continue choosing which of two statements is the better answer until the final question leaves you feeling pretty certain about a name. Of course you need to know some terminology and be able to see the small details that the questions are asking about. Keying plants almost qualifies as a sport: it takes practice, you will improve, and you often do better if somebody else is working with you to verify your choices, but books work too. The optimistically-titled Botany in a Day is a user-friendly introduction to the characteristics of plant families, and those basic characteristics will take you a long way toward starting to key plants.
Maybe it is better to suppose a family a day, and there are many families to learn. Before this sounds overwhelming, you'd like to know that being familiar with as few as 10 main families will get you started with lots of what you will be looking at! Still, if you bought a few books, a camera, and a maybe a dissecting scope, you could actually be set up for years of amateur botany for less than the cost of a single weekend in Wine Country or at Disneyland.
If you will learn just a few basic parts and their names, in very short order you will be seeing your garden in a new light. When you venture off for a look at wildflowers in some natural setting, be it a local park or a mountain pass, you will notice more about the flowers (plants) than ever before.
There are three main categories of flowering plants: trees, shrubs, and herbaceous plants (what most people simply call flowers!). Initially it took me by surprise to think of a tree as a plant, but I'm over that now. Within all these many types of plants there is yet one last major division of flower types: composites and not composites! Tip: if you have a flower that looks like a daisy or a dandelion, set it aside for now; that's a composite. If it looks like sweet pea, a pansy, or most anything else, presume that is in fact not a composite.
You can organize a deck of cards by first sorting the two colors, then sorting by the four suits (club, heart, diamond, spade) and finally by value. Plants are organized by characteristics of their flowers, and then other characteristics such as leaf arrangement, leaf shape, etc. Despite the many colorful guide books sold to ID flowers, a flower's color is seldom much of a concern when it comes to identification (though clearly in a mass of unknown flowers, a book like Peterson's Pacific States Wildflowers does a new botanist a service by grouping by color so there is an easy starting point. Later you will discover that color has as much potential to be confusing as to be helpful.)
Assuming your desire is to move beyond a flashcard approach (thumbing through a book of pictures as you look at real flowers), you will want to have a magnifier and a book that deals with your local flora. "Local" in this case can mean West Coast, Rocky Mountains, or East Coast. Ideally you will start by getting to know the major plant families, and a regional book is totally valid. After you get more comfortable, you can seek out a more specific book called a "flora" which catalogs a more localized vegetation (like your county or perhaps a regional park); it will be more technical and contain keys to identify plants.
A key is usually a list of paired questions, only one of which should be clearly a 'right' choice. Following to the next pair, and so on, you get to a final choice which should be the plant you are looking at. It takes time to learn to really recognize the small details needed to zero in on some absolute, but it is pretty easy to get familiar with enough information to get a mystery plant identified to family. For many people it is sufficient to simply know a flower is in a certain family, never mind the exact species.
A corpse flower
from Nat'l Geographic.
Here's How It Works:
During the Devonian Period (408-362 million years ago), seed-bearing plants developed and took two main directions: gymnosperms and angiosperms. The angiosperms developed an enveloped seed container and also developed an advertising method to bring pollinators to the scene. To trick a pollinator into visiting—and therefore carrying pollen to another plant—flowers developed colorful parts and sweet fragrances (or awful smells, depending on what the pollinators wanted!) Happy news for us humans, sweet smells trumped rotten smells as attractants, else we would be surrounded by more "corpse flowers", shown left, from National Geographic.!
As plants moved into new locations, or conditions changed, plants adapted, always developing ways to lure the pollinators, modifying their needs to exist in dry, or wet, or hot, or cold conditions. Some climbed trees, others took refuge in cracks in rock walls. When survival not only depends on leaving seeds behind but also not getting eaten before reproducing, being out of convenient reach becomes and advantage,
A few million years of remodeling and splitting into more specialized groups leaves a huge inventory of different solutions to different problems, even different solutions to the same problems (see PBS page on convergent evolution). All this adapting may radically alter the general look of a plant but the flowers stay pretty much unchanged with regard to parts, number of parts, and how the parts are hooked up.
Carl Linnaeus Devised a Method to Sort Things Out
The short version of this amazing story is that Linnaeus discovered that plants could look very unlike each other and yet their flower structures connected them as related. Wow! I think that is a briefly as this idea may have ever been described?
You can imagine the elegance of simply starting with the obvious: the flower. Flowers themselves are pretty basic. They have an ovule where seeds develop, they have stamens that produce pollen, and then most have advertising (colorful petals) to attract customers to come enjoy some nectar. The flower attracts a bug or a bird that pokes around for food and in turn gets pollen on its head or feet. When the critter moves on for another treat, that pollen is deposited in the next flower. Presto! Mission accomplished. Seeds develop and next year the precess repeats.
Parts Used to Establish Family Connections
[Refer to the flora: february page for illustrations of these parts]
The Pistil is the central part of the flower with an ovule at the base, and the style holding the stigma at the top. The stigma is the opening where pollen enters the tube (style) that leads to the ovules.
The Stamens are the filaments that hold the anther sacs containing pollen.
The Petals are the colorful parts that surround the stamens and pistil.
The Sepals are usually green parts that surround the flower bud, then open and are typically unnoticed as they ring the outside base of the flower.
The Leaves are obviously the green "food factories" that are arranged either as opposite pairs or alternating up the stems.
Plant families are identified by these few major parts; the number of petals, number of sepals; number of stamens, the type of pistil, and the arrangement of these parts are generally common to all members of a family, no matter how different the individual species might be. Example: apples and strawberries are in the Rose family:
Note that this picture is of a wild rose. Cultivated roses have been developed by modifying the abundant stamens to develop into petals. But rather than reinvent the wheel by trying to describe a process I don't understand, look at this:
“The petals can often be traced back to reorganized stamens. This interpretation is proven by the fact that links between both categories of structures exist. A classic example is the white water lily (Nymphaea alba, a rather primitive angiosperm) but such metamorphosis can, too, be found in many other species. Cultivators use this feature to select filled flowers. The wild rose (Rosa canina), for example, has only five petals and many stamens while most of the cultured varieties are characterized by filled flowers with many petals and a reduced number of fertile stamens.” — excerpted from the University of Hamburg page
And just to add to the fun, check this article about botanists discovering how to turn on the genetic change needed to make leaves turn into petals.