Earth & Environmental Sciences
cladistics
14%
climate change
13%
competition (biological)
6%
coniferous tree
5%
environmental change
19%
extinction
38%
flood basalt
5%
flora
63%
floristics
7%
fossil
10%
Guadalupian
12%
indicator
15%
land
12%
Lopingian
21%
loss
9%
mass extinction
33%
maturation
7%
new genus
23%
ocean
13%
organ
7%
peat
6%
Pennsylvanian
21%
Permian
100%
phylogenetics
18%
plant community
6%
plant species
9%
pollen
5%
province
7%
radiation
16%
Sakmarian
9%
seed
21%
stem
23%
symmetry
5%
topology
5%
volcanism
8%
xylem
29%
young
6%
Agriculture & Biology
case studies
19%
China
44%
coal
8%
flora
38%
fossils
9%
fronds
7%
Guadalupian epoch
7%
integument
6%
new genus
21%
ovules
32%
peat
8%
Permian period
13%
phylogeny
15%
pith
5%
plant communities
7%
resin canals
6%
secondary xylem
18%
Spermatophytina
7%
stems
16%
tuff
7%
vascular bundles
5%
wetland plants
6%
xylem
13%