MIAMI — They’re so easy to miss in a landscape almost monotonously green.

But for naturalist Roger Hammer, it’s the small, scattered drops of color that stand out among the slash pines and saw palmetto.

Wildflowers. The vast Everglades is home to hundreds of them.

Some are spectacular but most are small and subtle. Some are fragrant, others poisonous. With the exception of a few big names — notably, the rare ghost orchid made famous in a best-selling book — many are largely unknown and unnoticed, at least outside a small group of scientists, enthusiasts and, unfortunately, poachers.

“The average person driving by has no idea of what is out here,” said Hammer, as he hiked the northeastern corners of the Big Cypress National Preserve in an ongoing quest to find and photograph an exceptionally scarce yellow bloom called the Fakahatchee burmania.

If Hammer — a longtime Miami-Dade County parks naturalist and one of Florida’s foremost authorities on native plants — hasn’t seen an Everglades wildflower, then few other people in the world have.

Hammer, author of the 2002 field guide “Everglades Wildflowers,” has spent more than four decades walking, slogging and paddling across South Florida to document the region’s stunning array of wildflowers, many hidden in isolated mangrove jungles, steamy swamps and dense forests. Over the past three months, he has begun retracing often-arduous treks to complete a publisher-requested update that will include new, crisper digital photos of every wildflower and, he expects, add 30 to 40 new species to the more than 300 in the original guide.

It’s no secret that many and varied ecosystems of the Everglades serve as a hot house for rare and beautiful plants.

For decades, collectors pilfered rare orchids, bromeliads and ferns from the swamps and sloughs of South Florida, lands ostensibly under state or federal protection. Susan Orleans’ 2000 bestseller, “The Orchid Thief,” about obsessive collectors hunting the rare ghost orchid in the verdant Fakahatchee Strand, brought the black market to public light and, by Hammer’s assessment, at least helped curb poaching of the state’s botanical riches.

Florida boasts far more orchids than any other state, with some 108 species known to exist. Hammer, who was an expert source for Orleans and a non-poaching character in her book, was the first to discover two of those jewels growing in South Florida. But those delicate flowers are only part of the scenery. They are far outnumbered by hundreds of other wildflowers, many also beautiful or fascinating — particularly if you know what you are looking at.

On a trail through the pine flat woods of the Big Cypress’ Bear Island section, he pointed to a yellow daisy-like bloom, the tickseed. Despite its unappealing name, derived because its seeds resemble the odious insects, it’s the state’s official wildflower.

Further down the trail, he stopped at a common wildflower, the wild pennyroyal — a weedy-looking scrub topped by pea-sized cones of faint lavender flowers. When he crushed the needlelike leaves, which resemble fresh rosemary sprigs, the air filled with sweet scent.

“Take a whiff of this,” he said. “It makes a nice tea.”

At the still-moist edge of a depression marsh drying down after a long rainy season, Hammer stooped over a plant perhaps 6 inches tall with purple petals. The small butterwort seemed rather unremarkable until Hammer explained the meaning of its Latin name, Pinguicula pumila. The first word means “fat” as in the meaty kind, describing the greasy coating on the leaves of this carnivorous plant, a secretion that traps then digests insects.

Another dainty lavender-hued flower, the Glades Lobelia, sprouted only a few paces away. It was another kind of killer, producing a toxic narcotic sap that has medicinal uses but also can cause convulsions and even heart failure, Hammer said.

“Some of what is out here is edible,” Hammer said. “Some of it will drop you dead.”

Some Everglades wildflowers — like the white waterlily, which produce blooms as big as softballs that stand out in the marsh — are easy eye-catchers. But it can be difficult to even pick out many wildflowers against a backdrop that overwhelms, Hammer joked, with “all the shades of green and brown.”

Most of the winter blooms in the pine woods are no bigger than a quarter, typically nestled in few-and-far-between niches. They won’t wow most visitors, at least not compared with the sight of a gator lolling in the sun.

The Everglades also tends to hide many of its rarest and most attractive offerings in places most sane people simply do no want to go. Photographing a night-blooming cactus, for instance, Hammer had to crawl into mangroves in the dead of summer.

“I used to tell people I had to throw a rock through the mosquitoes to take the picture,” Hammer said.

For Hammer, who at 68 still regularly takes long solo canoe trips through the Everglades, the challenges make the rewards all the better. The key is knowing when and where to look, but even for experts, some things like the Fakahatchee burmania can remain elusive.

Two years ago, a colleague photographed the yellow bloom, only a few inches high, under a palmetto frond and kindly sent him the GPS coordinates. Hammer has returned during the same periods four times since but has struck out.

He’ll be back, he said. It took him five years to find one wildflower deep in a swamp.

“It’s a pretty good rush when you finally find something you’ve been looking for,” he said. “You want to look around and yell, “Hey, look at this!’ but then you realize the nearest person is 10 miles away.”