The crystal-clear waters of Shark Bay are home to the world's largest plant: a seagrass meadow spanning 77 square miles (200 square kilometers) and stretching 112 miles (180 kilometers) from end to end. The shoots that make up the massive meadow all originate from one stem, which researchers estimate is at least 4,500 years old.

Researchers analyzed the genetic makeup of the seagrass at Shark Bay for the first time in 2022. They discovered that almost all the Poseidon's ribbon weed (Posidonia australis) — which grows in a network of meadows inside the bay — was genetically identical, indicating that the weeds belonged to one plant. Unlike other types of seagrass, which reproduce sexually, this meadow appeared to be continually cloning itself through an underground stem called a rhizome.

Related: 2 plants randomly mated up to 1 million years ago to give rise to one of the world's most popular drinks

On the sandy seafloor, the self-cloning seagrass meadow forms clumps of grass that look like separate organisms, but underground, the shoots are connected to form "the largest clone in any environment on Earth," the researchers wrote in the study. 

This means the Shark Bay seagrass dwarfs the previous record-holder: The second-largest clone on record is a 9-mile-long (15 km) meadow of Posidonia oceanica seagrass in the western Mediterranean Sea. 

The meadow at Shark Bay is expanding through a process known as "horizontal rhizome extension," in which the plant grows stems that extend horizontally beneath the seafloor. These stems then grow vertical stems that develop shoots and leaves, which break through the sand to form seagrass. Based on the size and age of the meadow, researchers estimate it is expanding by around 6 to 14 inches (15 to 36 centimeters) per year — which is fairly quick compared with other self-cloning seagrass meadows, according to the study.

The meadow has remained relatively undisturbed for millennia, which has enabled it to reach colossal proportions. The clone could continue its creeping expansion for as long as it is left untouched, making it practically immortal, Elizabeth Sinclair, an evolutionary biologist at the University of Western Australia, previously told Live Science. 

This moss, named Syntrichia caninervis, lives in harsh environments across the planet, from the Mojave Desert to Antarctica. Now, a new study finds that it could survive in even nastier conditions. When subjected to a week in an environment like the surface of Mars, the researchers found that the hardy moss could bounce back. 

Its survival abilities may even outdo those of tardigrades, microscopic "water bears" that can live in the vacuum of space. The moss is better at handling heat — and can survive even higher doses of radiation — than tardigrades, the researchers said after subjecting the little moss to multiple ought-to-be-fatal indignities. 

"Our study shows that the environmental resilience of S. caninervis is superior to some of [the] highly stress-tolerant microorganisms and tardigrades," study researchers Daoyuan Zhang, Yuanming Zhang and Tingyun Kuang, of the Chinese Academy of Sciences (CAS), wrote in a statement. The researchers published their findings July 1 in the journal The Innovation. 

The team collected the moss from the Gurbantünggüt Desert in northern China. They first subjected samples of the moss to near-complete air-drying. Though the dried moss shriveled and turned black, it returned to full springy greenness within 20 seconds of rehydration. After 99% dehydration followed by rehydration, the moss returned to full photosynthetic capacity within two minutes, the scientists found. 

The moss also showed remarkable resilience against cold: After 30 days of immersion in liquid nitrogen at minus 320 degrees Fahrenheit (minus 196 degrees Celsius), the moss could recover and grow new branches. It could also survive for at least five years at minus 112 F (minus 80 C). While the moss rebounded fastest if it was dehydrated before freezing, it could also survive these conditions if frozen without being dried first. 

Finally, the researchers zapped the moss with massive amounts of gamma radiation. They found that the moss could survive up to 4,000 gray of ionizing radiation without much trouble. For comparison, 4 gray is considered a fatal dose of ionizing radiation for humans. (A dose of ionizing radiation is considered fatal when it kills half of those exposed to it.) For S. caninervis, the fatal dose is 5,000 gray. Even the hardy tardigrade tops out at 4,200 gray, the authors wrote. 

The moss can also handle hits from multiple stressors at once. The researchers put samples in the CAS Planetary Atmospheres Simulation Facility, which mimics the atmosphere of Mars in surface pressure, temperature, gas makeup and radiation. After seven days in this environment — mostly carbon dioxide, with temperature swings ranging from minus 76 F (minus 60 C) to 68 F (20 C) and hazardous levels of radiation — the moss still bounced back, recovering and growing new branches after 15 days back in Earth-like conditions. 

The findings suggest that the moss could be used in attempts to terraform Mars by introducing plants that can survive its harsh environment and create a more Earth-like surface and atmosphere, the researchers wrote.

The strange tree, which has been nicknamed the "walking tree" because it looks like it's striding across a field, is a northern rātā (Metrosideros robusta) — one of New Zealand's tallest flowering tree species that can live for up to 1,000 years. It's roots and long, arm-like branches make the tree look like an Ent — a fictional race of tree-like creatures that guard the forests of Middle-earth.

The tree stands alone in the middle of a large paddock next to a cemetery near Karamea on the west coast of South Island. It is around 105 feet (32 meters) tall — around the same height as a seven-story building, according to The New Zealand Tree Register.  

The walking tree was the clear winner of the 2024 edition of the New Zealand Arboricultural Association's (NZ Arb) Tree of the Year award, walking away with 42% of the public vote, which included five other finalists, according to a statement emailed to Live Science.

"It just strode out into the lead right from the very start," competition organizer Brad Cadwallader told Radio New Zealand.

The walking tree is an "exceptional feature" and a "prime example of the remarkable trees that we, as New Zealanders, are fortunate to experience," NZ Arb president Richie Hill said in the statement.

Related: The oldest tree in the world (and the 7 runner-ups)

It is unclear exactly how old the walking tree is, but award organizers noted it is the lone survivor of a forest that was cleared around 150 years ago. "The farming family back then clearly thought it was special because they left it," Cadwallader said.

Northern rātā trees are epiphytes — a type of tree that starts life growing on the surface of a host tree before growing aerial roots that eventually reach the ground. The walking tree likely began life high up in the canopy of its host, living off air and rainwater before reaching the ground. Its unusual root layout was likely caused by how it grew around its host tree, which probably died off centuries ago.

"That host tree has now gone," Cadwallader said. "Maybe the tree was either very, very big, or there may have been another tree that fell and lent against the host tree, and that's why the roots have split near the ground and given it that walking appearance."

Northern rātā trees are endemic to New Zealand and were once one of the most common species in the country's forests. However, their range has decreased over the last few decades and they are now listed as nationally vulnerable, according to the New Zealand Plant Conservation Network.

In addition to deforestation, the main threats to northern rātā are the invasive common brushtail possums (Trichosurus vulpecula), which destroy the trees by eating their leaves and gnawing at their roots. 

The trees are also threatened by hybridization with the closely related pōhutukawa trees (Metrosideros excelsa) and are susceptible to myrtle rust (Austropuccinia psidii) — a pathogenic fungi native to South America that was detected in New Zealand for the first time in 2017.

The majestic baobab tree can grow to heights of 82 feet (25 meters) and can live thousands of years. It is often dubbed "the tree of life" thanks to its amazing capacity to store water, provide food and even medicine from its leaves. 

However, the origins of the baobab (Adansonia) have been shrouded in mystery, in part because it's found in multiple regions. One species, Adansonia digitata is found in some 32 African countries, and another, A. gregorii, is found in northwestern Australia. The other six species are endemic to Madagascar.

Related: 'We were gobsmacked': 350 million-year-old tree fossils are unlike any scientists have ever seen

To untangle the plant's murky evolutionary history, researchers analyzed the genomes of all eight Adansonia species and then used data on their current distribution, as well as past climatic and geologic conditions, to recreate their emergence and spread.

The progenitor of the eight living species of baobab likely originated on the island of Madagascar around 41.1 million years ago, while the first baobab emerged 21 million years ago, the team reported in the new study, which was published Wednesday (May 15) in the journal Nature. The daughter species then diversified between 20.6 million and 12.6 million years ago, partly due to hybridization in a phenomenon known as reticulate evolution. Their separation into distinct species was also likely facilitated by mountain uplift and volcanism, which created new and unique habitat niches with their own climates and soil. 

How these trees then reached continental Africa and Australia is still unclear. In the past, some have proposed that baobab fruits may have been carried by ocean currents and, in the case of Australia, even transported by humans.

Also known as "upside-down trees" due to their sparse canopies, which resemble the root structures of other trees, baobabs are now threatened by drought and human interference, and three of the species are now listed as either endangered or critically endangered. 

Two of the endangered species, A. suarezensis and A. grandidieri, are highly inbred, according to the paper, presenting further complications for their survival. Volcanic activity and sea-level rise may have reduced the availability of their preferred habitat within the past 1 million years. Some of the current species are also in conflict, the paper notes. For instance, A. za and A. madagascariensis can thrive in a broader range of habitats and compete for territory with the endangered species, which have more specific demands.

About 60% of the world's coffee supply is sourced from Coffea arabica plants, which now grow in tropical regions across the world New research, published April 15 in the journal Nature Genetics, has revealed when and where the original C. arabica plants likely developed. 

Using population genomic modeling methods, the researchers determined that C. arabica evolved as a result of natural hybridization between two other species of coffee: C. eugenioides and C. canephora. The hybridization resulted in a polyploid genome, meaning each offspring contains two sets of chromosomes from each parent. This may have given C. arabica a survival advantage that enabled it to thrive and adapt.

"It's often argued that a hybrid polyploidy event can give an immediate evolutionary advantage given that two sets of chromosomes — and therefore two complete sets of genes — are inherited immediately after," study co-author Victor Albert, a biologist at the State University of New York at Buffalo, told Live Science. "Of course, it's always the case that duplicate genes are lost on the two genome halves of the polyploid, but there is always a net gain in gene numbers and therefore, possibly, a greater capacity to adapt to new environments."

Related: 'Living fossil' tree frozen in time for 66 million years being planted in secret locations

The researchers acknowledge that there is a margin of error. Earlier estimates of the time of hybridization date it as recently as 10,000 years ago. 

"We had to input an estimated mutation rate, and a generation time (seed to seed time). Together, these assumptions allow us to convert to calendar years. But these estimates are of course fraught with error ranges given the usual uncertainty on mutation rates and generation times," Albert said. Still, he thinks their estimate is reasonably accurate. The researchers used genetic information from 41 samples of C. arabica from various locations, including an 18th-century specimen.

Regardless of when it developed, this hybrid genome enabled the plant to flourish as it was cultivated across the world. It was originally believed to have been grown by humans in Ethiopia and then traded to the Middle East, where it was a well-known beverage by the 15th century. According to one legend, an Indian Sufi Muslim pilgrim smuggled seven seeds out of Yemen and established coffee farms in Karnataka, India around 1670.

Dutch traders began cultivating the plant in other regions — they first planted C. arabica on the island of Java in 1699 and one was sent to a botanical garden in Amsterdam in 1706. The Dutch and the French, with whom a plant was shared, also transported seedlings to their colonies in the 18th century. The offspring of the original plants are known as Typica while a mutation that occurred on the island of Reunion (then called Bourbon) resulted in another form called Bourbon. Most current C. arabica plants are derived from these two lineages, though a handful of wild ecotypes sourced from Ethiopia are also grown.

While the polyploid nature of its genome may have provided C. arabica with some advantages, it also left it vulnerable to disease, especially coffee leaf rust (Hemileia vastatrix). Genetic bottlenecks — drastic population reductions — due to climate variations reduced genetic diversity prior to human cultivation. The oldest bottleneck may have occurred 350,000 years ago and another at 5,000 years ago. The fact that all the current plants relate back to a single parent is another bottleneck.

"It's not as able to confront rust in an 'arms race' where genetic variation in Arabica meets evolving rust populations and fights back and forth to adapt to the disease. Instead, the rust has a greater capacity to adapt to any new resistance that evolves," Albert said. 

In 1927, C. arabica naturally crossed back to one of its parent species, C. canephora, on the island of Timor. This event created a more rust-resistant variety of coffee, but the quality of the beans has been deemed inferior to those produced by C. arabica or Robusta — another name for C. canephora.

Archaeologists made the discovery while conducting fieldwork in what was once the ancient Maya city of Yaxnohcah, on the Yucatán Peninsula. During excavations, they noticed a dark stain in the soil and collected samples of it, the team reported in the study, which was published Friday (April 26) in the journal PLOS One.

Back in the lab, researchers conducted an environmental DNA analysis of the soil, using a method they developed that involves collecting specimens in sealable, cryogenic tubes and preserving the samples as they are transported from the field to the lab. To preserve the samples, the researchers applied a solution called RNAlater, which helps to inhibit bacterial growth in the soil.

"It keeps the bacteria from eating DNA in there," lead author David Lentz, a professor of biological sciences at the University of Cincinnati, told Live Science.

The analysis revealed that the stain was actually the remnants of four types of plants, all of which have known "religious associations and medicinal properties" and were often used by the Maya, according to a statement from the University of Cincinnati. The botanicals included a morning glory known as xtabentun, which has hallucinogenic properties, as well as lancewood and chile peppers. The plants were then wrapped in the leaves of the jool plant — a common step in Maya rituals.

Related: Maya nobility performed bloodletting sacrifices to strengthen a 'dying' sun god during solar eclipses

"For the Maya, chile peppers were more than just a condiment and were often used in rituals and had medicinal applications," Lentz said. "Xtabentun has similar physiological effects as LSD, and we've seen evidence of its use in a ceremonial context. It turns out that this was a ceremonial bundle."

Researchers think the Maya likely made a ceremonial offering during the ball court's construction. The Maya were known for playing several ball games, sometimes called pok-a-tok, in which players and even royalty would use their bodies, but not their hands or feet, to hit a rubber ball.

But they also used the ball courts for ceremonial purposes.

"Today we think of ball courts as a place for recreation, but the Maya also saw them as sacred," Lentz said. "They would have placed the bundle while they were building the ball court as an offering to the gods to let them know that they were changing the landscape and to please bless it. This [ritual] coincides with similar ceremonies we've found evidence of at other [Maya] sites."

Based on the analysis, the researchers determined that the ceremonial bundle was placed at the site around A.D. 80, Lentz said.

The researchers were impressed that traces of the plants lasted nearly 2,000 years in a tropical climate.

"For the study, we collected about 5 grams [0.2 ounce] of soil, and in that, there were over 100,000 DNA sequences," Lentz said. "Of those, only 15 were from plants. It was pulling a needle out of a haystack."

The short answer is yes, and humans are responsible for the differences among these veggies.

"It is all one plant, Brassica oleracea, that humans have selected over multiple generations to have these varying vegetables that we all enjoy eating," Makenzie Mabry, an evolutionary biologist at the Florida Museum of Natural History, told Live Science.

Chris Pires, an evolutionary biologist who studies crop science at Colorado State University, calls these veggies "the dogs of the plant world." All pet dogs (Canis lupus familiaris) are the same species, domesticated from wolves (Canis lupus), and they come in different varieties, or breeds. Similarly, broccoli, cauliflower, kale and the other aforementioned vegetables were also domesticated from the same species, B. oleracea.

Related: Where did watermelons come from?

Of course, many crops were cultivated for specific traits too, such as heirloom tomatoes. But unlike those crops, which are bred for different colors, tastes and sizes, Brassica varieties are bred from the plant's different physical parts.

"We domesticated all of the plant parts," Pires noted. "The stem, the inflorescence [flower cluster], the leaf, the underground parts."

That domestication resulted in a wide range of nutritional diversity, too. As each variety adapted to different environments, it produced different amounts of antioxidants and bitter compounds, Alex McAlvay, an ethnobotanist at the New York Botanical Garden, told Live Science. Even the same vegetable can have different nutritional values depending on whether, and how, it's cooked. For example, "people have bred Brussels sprouts to be creamier, less bitter, more flavorful," Pires said.

And each veggie has had its bout of fame. In the U.S., kale only became popular for its so-called superfood properties in the past few decades, and in early 2024, The New York Times published a story about cabbage "having a moment."

Even beyond the seven main vegetables produced from B. oleracea, there are two to three dozen varieties that are specific to various regions of the world because different groups of people domesticated those plants locally. In the American South, for example, collards were brought over by European colonists and eventually became a staple of Southern cuisine. And the plant continues to develop in modern research labs; Broccolini, a cross between broccoli and Chinese broccoli (also known as Chinese kale), was introduced in 1993.

Scientists are still deciphering how and why humans artificially selected certain traits from different parts of B. oleracea. Those origins date back thousands of years, when our ancestors cultivated different parts of the plant — in some cases, by accident.

"They were weeds before they were crops," McAlvay said. As some societies cultivated the weeds with less-bitter leaves or more tender shoots, for example, those traits evolved into the crops farmers now grow commercially.

One reason it's difficult to trace that ancestry is because the climate and environment 2,000 years ago were vastly different than they are today, Pires noted. He and Mabry worked on a study in which they attempted to trace those lineages. They found evidence that Brassica cretica, a flowering Mediterranean plant, is the closest living relative of B. oleracea. Despite their progress, the picture remains incomplete.

"How do you figure out the origins of something where you don't even know what the ancestor looks like?" Pires said.

Our current understanding of the Brassica family tree would crumble in an instant if another ancestral variety were discovered, for example, or if archaeologists sequenced the ancient DNA of a fossilized relative, Pires said. Our evolutionary understanding of the species is constantly changing.

Another reason for the mystery is the way crops evolve. Once humans cultivate plants, they can later become feral if abandoned, Mabry said. Crops can also turn feral if they hybridize with nearby wild varieties through cross-pollination. Wild plants, by contrast, have never been cultivated. In this sense, B. oleracea has become an important research model for scientists' understanding of hybridization and larger evolutionary processes.

The coolest thing about this plant? "Everyone grows these in their backyard," Mabry said, noting that it's a go-to beginner crop for home gardeners. "I think we have a real close connection to this plant as a society."

The new discovery highlights differences between the two ecosystems, suggesting forests went from being relatively primitive to well established over the course of just a few million years, said Neil Davies, the lead author of a new study published Feb. 23 in the Journal of the Geological Society.

"Why it's important — broadly — is it ticks the boxes of being the oldest fossil forest," Davies, a professor in the Department of Earth Sciences at the University of Cambridge in the U.K., told Live Science. The finding is also remarkable because it reveals stark differences between the complex array of ancient plants found at Gilboa and the newly discovered forest, which appears to have hosted just one type of plant, Davies said.

This now-extinct type of plants, known as cladoxylopsids, is thought to be closely related to ferns and sphenopsids (horsetails). "They look like palm trees, but they're in no way related to palm trees," Davies said. "They've got a long central stem and what look like palm fronds coming off, but those palm fronds aren't really leaves — they're actually just lots of twiglets."

Related: 'Living fossil' tree frozen in time for 66 million years being planted in secret locations

These twig-crowned trees would have stood between around 6.5 and 13 feet (2 to 4 meters) high, meaning "it wouldn't have been a very tall forest," Davies said.

The fossil trees were preserved both as hollow trunks filled with sediment and as fallen logs that were flattened over the eons — like "casts inside the sediment," Davies said. Little scars where branches used to attach to the trees are still visible, he added.

Davies and his colleagues stumbled upon the forest remnants during fieldwork in the Hangman Sandstone Formation, which dates to the Middle Devonian period (393 million to 383 million years ago). During the Devonian period, what is now the U.K. formed part of a continent called Laurentia that sat just below the equator, meaning the climate was warm and dry, Davies said.

"When I first saw pictures of the tree trunks I immediately knew what they were, based on 30 years of studying this type of tree worldwide," study co-author Christopher Berry, a paleobotanist and senior lecturer at the University of Cardiff in the U.K., said in a statement. "It was amazing to see them so near to home. But the most revealing insight comes from seeing, for the first time, these trees in the positions where they grew."

Older trees exist elsewhere in the world, with plants first colonizing land 500 million years ago, but this new discovery is the earliest example of a forest with trees growing close together and en masse. 

"We've found rocks where you've got standing trees in growth positions adjacent to each other over a set area," Davies said, "so we're looking at a snapshot where we can tell for definite that there were trees growing in that specific location and that the sediment we're looking at is the forest floor."

Among the fossil trees, the researchers found trackways belonging to small Devonian critters. "At this time, there's nothing much bigger than lots of little arthropods knocking around on land," Davies said. "You might find some more amphibian-type things and fish in some of the lakes and rivers nearby."

While the researchers had initially set out to examine sediments, the fortuitous discovery of fossil trees may reveal a turning point in Devonian plant ecology. "It kind of suggests that around 390 million years ago, there is this sudden takeoff in forest-type environments," Davies said.

Editor's note: This article was updated at 08:20 E.T. on March 8th to include comments from co-author Christopher Berry and an illustration of the fossilized forest.

Wollemi pines (Wollemia nobilis) were believed to have disappeared some 2 million years ago. Fossils of the species dating the Cretaceous period (145 million to 66 million years ago) show they have barely changed in appearance since this time. 

But in 1994, hikers in Australia's Blue Mountains stumbled upon a relict stand of these ancient conifers. Now, only around 60 of them remain in Wollemi National Park. They are threatened by Phytophthora cinnamomi, a pathogenic water mold that causes dieback, and by rampant wildfires that intermittently rage through this region of New South Wales.

Since its rediscovery, wollemi pines have been grown in botanical gardens and private spaces around the world. And the Wollemi Pine Recovery Team, a partnership between Australian government scientists and conservationists, has begun the process of reintroducing seedlings to three sites in Wollemi National Park.

Related: Living fossils — 12 creatures that look the same now as they did millions of years ago

"The sites comprise high-elevation sandstone gorges that are sufficiently deep, narrow and steep-sided to provide refugia from frequent, intense wildfires and drought," representatives said in a statement emailed to Live Science. "There was no evidence of infection with pathogenic Phytophthora species at either site when surveyed immediately prior to the translocations, and there is a low (but non-zero) likelihood of unauthorized visitation due to their remoteness."

Following a pilot transplantation effort in 2012, the recovery team initiated a more intensive project in 2019. Over 400 saplings were transplanted at two sites and — due to drought conditions — the team later hauled several thousand gallons of water to the plants in order to help them survive. Later that year, a substantial number of the trees were destroyed by bushfires. Only 58 saplings made it to 2023.

In 2021, 502 more Wollemi pines were planted at the sites to replace those lost in the fires. "Survival has greatly exceeded expectations, due in part to several years of favorable La Niña conditions following the 2021 population augmentations," the researchers said. La Niña is a periodic climate pattern that features colder-than-average waters in the central and east-central equatorial Pacific. Increased rainfalls due to the climatic phenomenon benefited the new transplants—but that seems to be coming to an end. Landslides caused by heavy rains in 2022 led to further fatalities but more than 80% survived. More will be planted in 2024.

The team has taken extensive steps to prevent introduction of Phytophthora to the sites. Their locations are concealed from the public and even the reintroduction team limits their time near the plants. They repeatedly disinfect their shoes to reduce the likelihood they will track in traces of the water mold. Even a few spores might spell death for this nascent population.

They have also intentionally located some of the young trees in areas that might be subject to bushfires "to help address knowledge gaps regarding their response and ability to tolerate fire," the team said.

While the new populations are being intensively monitored, the fate of the species in the wild is far from assured. The young trees grow less than 0.4 inches (1 centimeter) a year, so it will take decades for them to reach maturity and produce seeds. Some may produce offshoots in the meantime, though when they may begin propagating themselves in this fashion remains unknown. 

Fires and other climate-related issues such as reduced rainfall are likely to interfere with the restoration effort in the coming years. The scientists view their effort as a multi-generational one: a new cohort of stewards will need to take their place in the ensuing decades. 

"To be successful, the translocated populations must become self-sustaining, and the benchmark is the appearance of second-generation seedlings," the researchers said. "Given the slow growth and maturation of Wollemi pines in the wild, this is likely to take many decades, if not centuries. Given predicted increases in the frequency and severity of fire and drought due to climate change — arguably the two greatest threats to these populations — their long-term security is far from guaranteed."

But how do insects know where to find pollen? In theory, the process is easy: A flower flaunts bits of tasty, aromatic dust in plain sight, letting pollinators know where to go right away. But the reality is quite different. "It's not in the plant's interest to emit an honest signal," said Casper van der Kooi, a biologist who studies flower color evolution at the University of Groningen in the Netherlands.

For plants, pollen is about reproduction. The goal of creating this powder is to transfer a flower's gametes, or reproductive cells, to another flower to create a seed. Plants often need pollinators for that job, but it takes a lot of energy and nutrients to make pollen. So, if insects end up eating the pollen, or if the wrong pollinators get to it first, the energy the plant has invested goes to waste, van der Kooi explained.

So, for most plants, pollen is hidden, making an insect's mission harder to accomplish. But a plant can't be too dishonest, van der Kooi said; otherwise, the insects will learn of this deception and stop visiting the plant. So, instead of communicating directly, plants often use subtle signals to convey information, said Natalie Hempel de Ibarra, a professor who researches the behavior, senses and cognition of social insects at the University of Exeter in the U.K. Insects then pick up on certain cues to decide which flowers to visit.

Visual cues are one of the main forms of plant-pollinator communication. Flowers are colorful, and insects have this innate affinity to colorful objects, Hempel de Ibarra said. Some flowers have so-called nectar guides, which are patterns, visible only in the ultraviolet spectrum, that illuminate a path to the nectar and/or pollen that an insect can follow. Various studies have documented that these nectar guides, as well as the hue of the flowers themselves, can change color as pollen and nectar supplies decrease. Lantana camara, a popular garden plant, is an example of this type of signaling, turning yellow to red.

Related: Do bees really die if they sting you?

Smell can also indicate the amount of pollen. Flowers release all sorts of chemical compounds into the air, and insects can pick up on these so-called olfactory cues. Some plants can adjust the amounts of compounds they release as an additional signal. For example, blueberry flowers have evolved to emit a lower amount of compounds after being pollinated, according to a 2011 study in the journal Annals of Botany.

Pollinating insects can also detect other subtle signals. One interesting example is the electric field. Flowers have a weak electric field, Hempel de Ibarra said, and this field is affected by the shape of the flower. It can also be disrupted after an insect visits it. Research has shown that bumblebees and some other insects can pick up this disruption using specialized hairs.

But ultimately, how insects make their pollen-finding decisions varies widely among species. Flowers can also evolve highly specialized relationships with specific pollinators, thus influencing how insects make their choices. Some flowers, like dandelions, have their pollen in plain sight, attracting a whole suite of pollinators, Hempel de Ibarra said. But tomato flowers, which rely specifically on bees to be buzz pollinated, hide their pollen in special structures to attract this specific insect.

In addition, different insects are attracted to specific colors, van der Kooi said. For example, flies tend to gravitate toward yellow, whereas bees prefer blue.

Decision-making can even vary among individuals. Hempel de Ibarra, who studies bees, said that individuals within a social colony can make different decisions in pollen gathering as they learn and experience the environment around them. "That makes it quite complicated for the bees to decide what kind of pollen it should be collecting," she said. "It's such an intricate relationship."