National Geographic - UK (2022-05)

Cladoxylopsid trees

Archaeopteris trees

Modern trees

Guangdedendron

Lycopsid trees

400 MYA TODAY

DEVONIAN PERIOD
(419-359 MYA)

Archaeopteris

tree

Cladoxylopsid

tree

Other roots from the period

Main roots

split into

pairs

Rootlet Hollow

BUILDING BETTER ROOTS
Early tree types had increasingly
sophisticated root systems. While
the simple radiating roots of
cladoxylopsids limited the trees’
size, branching roots supported
greater weight and height.

Guangdedendron’s

main roots divided in

two. Lateral rootlets

were likely hollow to

carry air in the oxygen-

poor environment.

EARLIEST TREES
The first major tree types all
went extinct, but Archaeopteris
is an indirect ancestor of today’s
trees. The group that includes
Guangdedendron, the lycopsids,
survives as much smaller plants.

SOURCES: “THE MOST EXTENSIVE DEVONIAN FOSSIL FOREST WITH SMALL LYCOPSID TREES BEARING THE EARLIEST STIGMARIAN ROOTS,” CURRENT BIOLOGY; CHRIS BERRY,
CARDIFF UNIVERSITY; PATRICIA GENSEL, UNIVERSITY OF NORTH CAROLINA AT CHAPEL HILL; GAVIN FOSTER, UNIVERSITY OF SOUTHAMPTON; BRIGITTE MEYER-BERTHAUD,
CNRS; ERNEST M. GIFFORD AND ADRIANCE S. FOSTER, MORPHOLOGY AND EVOLUTION OF VASCULAR PLANTS; YOU-AN ZHU, CHINESE ACADEMY OF SCIENCES; NOAA