MIAMI (AP) _ Killing endangered animals can mean prison, but landowners may with impunity pluck or bulldoze the last specimen of the rarest plant on Earth.

Federal and state agencies keep lists of hundreds of endangered plants, some discovered so recently they haven't been given Latin names. Yet laws that prohibit even molesting endangered animals regulate only those plants on public land and the theft or sale of rare flora.

''We are pointing our fingers at the developing nations of the world, saying, 'How can you destroy your rain forests,' yet here we are allowing our own plant species to become extinct,'' says Jora Young, director of stewardship for the Nature Conservancy in Florida.

The lack of concern for plants is ironic, ecologists say, since plants have been more useful than have animals. Besides providing most of the food we eat, they produce morphine, aspirin, digitalis, atropine, alcohol, mustard, menthol, quinine, curare, germicides, pesticides and scores of other useful substances.

''A lot of plants may not be important now, but they may some day save lives,'' says Richard Wunderlin, president of the Florida Native Plant Society.

Florida ranks third in the nation for the number of endangered plants, behind California and Texas, Wunderlin said. It also boasts, at least for now, many rare species found nowhere else in the country, or even the world.

In Florida, the problem is acute. Booming development is wiping out native plant habitats from the hardwood hammocks in the tropical Keys to scrub land in central Florida and pine woods along the Apalachicola River.

The state has created an Endangered Plant Advisory Council, but its powers are limited to placing species on a list that merely regulates their sale.

''We're adding more plants to the list all the time,'' says council Chairman Dan Austin, a botany professor at Florida Atlantic University in Boca Raton. ''But it doesn't protect the plants. People can do just about anything they want, and nobody outside can stop them.''

Many environmentalists have given up on crowded southeastern Florida. Austin said only 1 percent of the native scrub land in Palm Beach County still survives; in Broward County it has all but disappeared. The main battleground is now central Florida, where rare plant species are succumbing not only to development but to the spread of the citrus industry.

Wunderlin points in frustration to a newly discovered species of the rattlebox plant that is so new it doesn't even have a scientific name. It is known only in two locations - both housing developments near Avon Park.

''The species is disappearing lot by lot. We will propose it be put on the federal protective list but it's still on private property, so that won't protect it at all. Each time we go into the fields, more have disappeared.''

The federal government lists only 27 plants for protection. Plants on the list can't be destroyed if they are found on a federally funded project such as a dam or public housing. But that represents a tiny fraction of the development in most areas, Austin said. The state does not have any similar prohibitions for the 139 endangered and 280 threatened plants on its list.

Placing a plant on the list isn't always easy because development and farm interests routinely oppose such efforts, Austin said. It also gives landowners who find endangered plants on property they intend to develop an incentive to destroy them quickly to avoid later headaches. That's perfectly legal.

''If you're a developer and you own the last population of the big pine partridge pea, you can bulldoze it,'' said Ms. Young. ''As long as you don't steal if from a federal preserve or try to sell it, you're OK.''

Plants have historically gotten short shrift. Under old English law, animals, which moved through the property of many people, belonged to the crown, making them in effect a public trust. But plants remained on one spot and were totally the property of the landowner.

And people, being animals themselves, are subject to what Ms. Young called ''the Bambi syndrome.''

''If I talk about the impending extinction of the Key deer, people say, 'Oh, that's terrible. What can we do,'' she said. ''But if I say, 'This little mint that occurs only in two places on the Lake Wales Ridge is very close to extinction,' they just shrug and say, 'That's too bad.'''

That prejudice, she said, is not based on reality. Besides their value to humans, lower plants are often food for higher animals, and their destruction can have unknown implications on the environment.

Although state officials and environmentalists see little hope for a sudden broad shift in the legal and political climate, there are some hopeful signs.

Dade County has begun to protect some native trees, although without protecting the habitat they need to survive, said Julia Morton, a University of Miami biologist. ''It's only quantitative, dealing with numbers.''

Another alternative Ms. Morton found hopeful is transplanting rare species to exotic plant nurseries, if the developing landowner agrees.

That approach, while often the only realistic one, is inadequate, Wunderlin said. ''In the wild they are very variable genetically. By removing only a few plants and cultivating them, you are preserving only a very small proportion.''

If they are reintroduced they can't resist extreme conditions, he added.

Environentalists and experts unanimously praised the Nature Conservancy, which has bought 400,000 acres of environmentally sensitive land around Florida over the last 25 years. It often acts as an agent for the state, quickly buying the land and then holding it until the state bureaucracy is ready to buy it.

The Conservancy recently bought a site along the Apalachicola River that is the last refuge of an endangered evergreen tree. It has preserved ancient dunes in the Lake Wales Ridge area that are the only known home of endangered species such as the scrub plum and the pygmy fringe tree. And it is buying hammock areas on Key Largo that harbor a variety of tree and plant species.

Despite an increase in environmental consciousness, Austin said, protecting animals while ignoring plants is ''like a watchmaker taking a watch apart and throwing half the pieces away then trying to put it back together.''

Each day, environmentalists say, more pieces of the watch are disappearing.