From the Diary of a Cone-oisseur

By Nidhi Patel, PhD candidate, Stanford University

Did you know that long before flowers bloomed across the Earth, the world already had vibrant color in the form of young conifer cones? Before any magnolias, sunflowers, or orchids evolved, ancient conifers were reproducing with remarkable structures that still surround us today. While you might be familiar with the woody pinecones scattered on forest floors, many people overlook the young cones that appear each spring on plants such as Abies nordmannianna and Pinus muricata. Blooming in unexpected shades of ruby red, deep purple, hot pink, or bright yellow-green, they briefly turn ordinary branches into brilliant seasonal displays.

Nidhi Patel at the UC Botanical Garden at Berkeley

As a PhD candidate studying plant evolution, my playground spans millions of years. While we can learn an immense amount about evolutionary processes by studying living plants, they are often too highly derived; meaning they have changed and specialized over deep time. To understand how vastly these modern forms have diverged from their extinct ancestors, I regularly visit the breathtaking collection at the University of California  Botanical Garden at Berkeley to gather fresh samples.

Peering Inside the Young Cones
Back in the lab at Stanford University, I use high tech Micro CT scanning, which is essentially an X-ray, to look inside these young cones without cutting them open. This allows me to map their complete surface and even study individual organs using advanced topological methods, revealing the hidden architecture of these plants and their reproductive displays. My research focuses on the exact moment when conifer reproduction begins. Unlike flowering plants, conifers do not hide their ovules (the tiny structures that become seeds), inside a protective ovary. Instead, their ovules are completely exposed, hence, the name ‘gymnosperm’, a Greek word meaning ‘naked seeds’.

Image 1: Colored 3D reconstructions of micro-CT imaging of Cupressaceae ovulate (female) cones at pollination stage. A. Chamaecyparis obtusa. B. Hesperocyparis pygmaea. C. Cryptomeria japonica. D. Sequoia sempervirens.

Conifer Pollination
Conifers rely entirely on the wind for pollination. Therefore, nature has designed their pollen to be incredibly buoyant. Each tiny grain (in pine and podocarp family) features air filled bladders that act like miniature hot air balloons, helping the pollen drift effortlessly through the breeze. The young female cones produce ovules borne on scales along with a bract, which are repeated and can be arranged spirally on the cone. This architecture varies dramatically across species and families. To catch these floating grains, each ovule secretes a pollination drop. The sticky droplet acts like a net, trapping the airborne pollen for fertilization.

What makes cones so spectacular is how much they transform over time. Early in their development, the cone’s scales are often spread to catch the pollen. Once fertilized, the scales tightly lock together to protect the growing seeds. Finally, when the seeds are mature, the cone dries out and reopens to release them into the world. The next time you walk through a botanical garden, take a closer look at the branches. Those tiny flashes of spring color are actually living history, ancient, sophisticated dynamic systems that have shaped our planet’s ecosystems for over 300 million years.

Cartoon depicting ovule position and associated organs. A. In most Pinaceae, the ovule is inverted, borne on the ovuliferous scale subtended by a bract. B. In Cupressaceae, the ovule is upright, borne on a bract-scale complex (ovuliferous scale and bract are congenitally fused).

Pollination stage ovulate cones of A. Abies nordmanniana. B. Pinus muricata. C. Cupressus sempervirens.