The Surprising Map of Plants

An oak tree is more closely related to a pumpkin than to pine trees, challenging the traditional view of plant evolution. The concept of an evolutionary tree has changed over time, reflecting new understandings in botany. This video explores the relationships among various plants on Earth and presents an evolutionary map created with experts from the Royal Botanic Gardens Kew in London. The map organizes plants based on their evolutionary history, illustrating how all plant life is interconnected.

Algae encompass a diverse range of organisms capable of photosynthesis, varying from single-celled diatoms to multicellular seaweeds. While not all algae are classified as true plants, they play a crucial role in oxygen production—contributing about one-third of the atmosphere's oxygen through phytoplankton. Red algae represent an early group within the plant kingdom with around 6,000 species; however, their evolutionary origins alongside glycophytes remain debated. The defining feature that classifies something as a plant is its chloroplasts—organelles responsible for photosynthesis—which evolved from an ancient symbiotic event between two cells. Algae exhibit different colors due to various pigments used in energy conversion and share common ancestry with land plants dating back approximately one billion years.

Bryophytes, including mosses, hornworts, and liverworts, are essential for understanding plant evolution as they resemble the earliest land-dwelling organisms from around 470 million years ago. They lack advanced features like flowers or vascular tissues but possess root-like structures called rhizoids. These plants thrive in moist environments since they absorb water directly through their cells; some mosses can take up to 20 times their weight in water. Typically small at about 3 to 6 cm tall, bryophytes do not have the structural rigidity provided by vascular tissues found in more modern plants.

Vascular plants, which first appeared around 420 million years ago, have specialized tissues called xylem and phloem that transport water and nutrients. This vascular structure allows them to grow taller than nonvascular plants, with a maximum height of about 60 cm for the latter. Club mosses are distinct from true mosses due to their vascular system but differ from ferns in leaf structure and DNA. Ferns include various types such as whisk ferns and horse tails; they reproduce through spores rather than seeds. With over 10,000 species worldwide—including some underwater—ferns once dominated ancient forests with ancestors reaching heights of up to 40 meters.

Seed plants, specifically gymnosperms, represent a significant evolutionary advancement as they reproduce using seeds instead of spores. A seed consists of an embryo, nutritive tissue, and a protective covering. Gymnosperms include major groups like Ginkgo and conifers such as pines and spruces; they first appeared in the fossil record around 390 million years ago. These plants reproduce through male cones that produce pollen and female cones containing ovules which develop into naked seeds after fertilization. Their well-developed vascular tissues allow them to grow tall in diverse environments; for instance, conifers have needle-like leaves adapted to conserve water in cold climates.

Fungi, often mistaken for plants due to their appearance, are genetically closer to animals and do not photosynthesize. They play a crucial role in ecosystems through symbiotic relationships with plants known as mycorrhizae. In this partnership, fungi provide essential nutrients like water and phosphorus while receiving organic molecules from the plant's photosynthesis. Additionally, when plants die, fungi decompose them and recycle nutrients back into the soil. Lichens represent another unique relationship between algae and fungi.

Angiosperms, or flowering plants, emerged around 135 million years ago and now represent the most diverse group of land plants on Earth. Approximately 90% of flowers are designed for animal pollination, creating a symbiotic relationship where animals feed on nectar or fruit. The reproductive process involves pollen (male) meeting an egg (female), resulting in an embryo that develops into a seed within the ovary; this then transforms into fruit to protect and disperse seeds through various methods like animal consumption or wind transport. Fruits encompass any edible item containing seeds—like plums and cucumbers—and can be classified as hard fruits with protective shells or false fruits such as apples that originate from other plant parts rather than ovaries.

Early diverging angiosperms provide insights into the characteristics of ancestral flowering plants. Key groups include Amborella, a single-species plant; Nymphaeales, which encompasses water lilies and other aquatic species; and various families like Piperaceae for black pepper, Magnoliaceae (magnolias), and Lauraceae (laurels). These early types illustrate the foundational traits of flowering plants that emerged in ancient ecosystems.

Monocots, a group of flowering plants that emerged 140 to 125 million years ago, include diverse species such as pondweeds, yams, orchids, and grasses. Notably significant are the grasses which encompass essential cereal crops like corn, wheat, rice, and barley—contributing to half of human food supply and occupying one-fifth of Earth's land. The monocot family boasts approximately 85,000 species in total; astonishingly nearly half are various types of orchids with around 30 thousand distinct varieties.

Eudicots and monocots are the two major groups of flowering plants, with eudicots being the most diverse group that emerged around 125 million years ago. Eudicots can be divided into three subsections: early diverging eudicots, rosids, and asterids. The terms 'monocot' and 'eudicot' refer to the number of seedling leaves; monocots have one leaf while eudicots have two. Additionally, all eudicats share a unique pollen type known as triculate due to its three grooves.

Early diverging eudicots include a diverse range of plants such as buttercups, poppies, and proteas like lotuses. Notable among them are gunas with exceptionally large leaves and various mistletoes alongside spiky cacti that possess needle-like spines. Cacti share a connection to carnivorous plants like the Venus flytrap; over 700 species have evolved mechanisms to trap animals for nutrients in nutrient-poor environments. These adaptations can involve rapid closure or sticky surfaces designed to ensnare prey as substantial as mice. Additionally, saxifrages encompass stone crops and peonies which were recently linked through DNA evidence despite their mysterious relationships.

Rosids emerged around 100 million years ago, encompassing approximately 90,000 species globally. Key groups include grapevines, geraniums, fuchsias related to pomegranates; passion vines linked with violets; wood sorrels and roses associated with figs and cannabis; legumes like peas and beans; oaks connected to walnut trees; squash plants including pumpkins; hibiscuses tied to cacao for chocolate production; maples related to horse chestnuts. A significant group is the brassicas which have been selectively bred into various vegetables such as cabbage and broccoli from a single ancestor. Despite over 880,000 edible plant species worldwide, about 90% of our food comes from just thirty plants due to many being inedible or toxic.

Asterids encompass around 100,000 diverse species that emerged approximately 89 million years ago. This group includes dogwoods, tea plants, coffee relatives, forget-me-nots, mints, potatoes (related to morning glories and chili peppers), hollyhocks (originally inedible before breeding), honeysuckles, viburnums and asters like sunflowers and dandelions. Notably, a sunflower is composed of many small flowers called florets that each develop into individual seeds.

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