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12 Days of Conifers: Conifer Trees and How We Study Them

You might have an evergreen tree in your home or workplace this month, but here at USGS, many of our scientists get to enjoy beautiful pines, firs, and cypresses year round in their outdoor workplaces! In this series, we'll explore what conifers are and how USGS scientists study them. To start: what exactly is a conifer?

Conifers are trees that bear their seeds in cones (hence the name conifer). The vast majority of conifers have needle-like (e.g. pine or fir) or scale-like leaves (e.g. cypress or juniper). Most conifer species keep their needles all year, so we often refer to these trees as “evergreen” (larches are an exception).

Pinecone with tightly closed scales attached near the top of a pine tree.
A closed lodgepole pinecone on a tree in the Sierra Nevada.

Conifers are an ancient group of plants, splitting off from close relatives like ginkgos and cycads more than 300 million years ago. Before the evolution of flowering plants, conifers dominated forests around the world. One of the photos at the bottom of this post shows conifer fossils from the time of the dinosaurs!

Today, there are about 615 conifer species. Though we often associate evergreen trees with cold, snowy, forests, conifers can be found in all kinds of temperate, arid and tropical ecosystems, such as shrublands, savannas, and even swamps. Conifers include some of the world’s most iconic trees, including the tallest tree, the oldest tree, and the biggest tree by volume, all of which are found in California. But there are extraordinary conifers around the world—from California's redwoods to the South American monkey puzzle tree, both pictured at the bottom of this post.

Conifers are the foundation of many of California’s forests. They store carbon and provide habitat and food for animals and other organisms. They give humans shade and lumber and firewood and pine nuts and juniper berries. But many conifer populations and species are threatened today by climate change, wildfires, pests, drought, and deforestation.

Snow covered conifer trees, densely packed on a deeply snowy hillside
Snowy conifers in the Sierra Nevada

USGS scientists and partners conduct research across California to better understand the ecology of conifers and conifer forests and the threats they face. For each day of 12 Days of Conifers, we are featuring different conifer species and research. Click the links below to read each part of the series:

Coring the Prickly Ponderosa

Five Needles on a Foxtail

How to Measure a Giant Sequoia

The Goldilocks Cones of Tecate Cypress

Red Firs in the Forest

Pinyon, Juniper, and the Greater Sage-Grouse

Whitebark at Risk

A Tale of Two Conifers: Incense Cedar and Sugar Pine

Pines of Santa Rosa Island's Cloud Forests

Lodgepole Pines and Mountain Meadows

Where the Forest Meets the Sea: Seabirds, Conifers, and Wildfire

Bonus: Spiky Leaves Aren't Just For Conifers


Rocks show two different types of fossil conifer branches, one with needle-like leaves and one with broad leaves
Fossils of the Mesozoic conifers Sphenolepis and Podozamites.
Conifer tree that resembles pipe cleaners stuck together, with needles sticking straight out from the trunk and branches.
Monkey puzzle tree, a South American conifer, photographed in a botanical garden in New Zealand.There are over 600 species of conifers around the world, and they exhibit enormous diversity.
Seven tall redwood trees crowded together into a semicircle, a cathedral of trees
Redwood trees in northern California forming a fairy ring, a product of redwoods resprouting around a stump.

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