Diversification of conifers - Origins of modern families

Subdivision: Coniferophytina
Class: Cordaitopsida*
Order: Cordaitales - cordaites
Class: Coniferopsida
Order: Voltziales* – transition conifers
Order: Coniferales – conifers
*fossil group
Small trees
Cordaitales
Cordaite reconstructions
Tree-sized mangroves with
prop roots
Prostrate, scrambling plants
Cordaianthus
Pollen sacs
Cordaianthus
reproductive structures
Name for both pollen &
Seed bearing structures
Pollen bearing cone
(these used to be called
“inflorescences”
They are loose cones
These structures are
compound
Short
shoots
bract
Stalked
ovules
Pollen of Cordaianthus
Gothania –another cordaite
pollen cone
TEM of pollen
Florinites - pollen
is monosaccate
Subdivision: Coniferophytina
Conifers– cone-bearing
plants
Araucaria araucana – monkey puzzle tree
Tsuga canadensis
Coniferophytina
• Order: Coniferales
– Family: Araucariaceae
– Family: Podocarpaceae
– Family: Phyllocladaceae
– Family: Cupressaceae (incl. Taxodiaceae)
– Family:
– Family:
– Family:
– Family:
Taxaceae
Cephalotaxaceae
Sciadopityaceae
Pinaceae -Northern Hemisphere
Characters used to delimit conifer
families
Growth habit
Cone shape
Cone construction/morphology
Number of seeds/ovuliferous scale
Number of pollen sacs/microsporophyll
Leaf morphology and venation
Pollen morphology
Seed morphology
Growth habits of conifers
Cupressaceae/taxodiaceous
Podocarpaceae
Dacrydium guillaminii – endangered shrub
Sequoiadendron –big tree
Araucarian conifers on Les ÎIes des Pins, New Caledonia (Araucariaceae)
Agathis lanceolata
Agathis ovata
Araucariaceae
New Caledonian endemics
Cupressaceae
Parasitaxus ustus
– the only known parasitic conifer
Leaf variability in conifers
Agathis
Araucaria
Araucaria
Araucariaceae
Sequoia taxodiaceous Cupressaceae
Picea (spruce) Pinaceae
Tsuga canadensis leaves
Pinaceae
needle-like
C
U
P
R
E
S
S
A
C
E
A
E
Taxodium
Larix (larch) short shoots with a large number of leaves/fascicle
Pinus strobus showing short shoots (=dwarf shoots) with fascicles of needles
Pinus
sylvestris
Long shoot
bearing
short shoots
in the axils
of scale leaves
Pinus leaves in fascicles
2
5
3
Pinus
leaves
Pollen
cones
Pinaceae cones
Pine pollen cone
a simple structure with leaves
that bear 2 abaxial pollen sacs
Pine pollen &
microgametophytes
Pollen tube
Corpus=body
Saccus=air bladder
used to orient grain in
the pollination droplet
saccus
corpus
distal
surface
Conifer pollen
Podocarpaceae
Cupressaaceae
Araucariaceae
Pinaceae
Agathis australis
Owens et al. 1998
Conifer cone variability
Pseudotsuga
Thuja
b
os
Douglas fir
hemlock
Pinus
ovulate cone
(seed cone)
These cones are compound
Ovuliferous scale
Bract
Together these two make up
the cone-scale complex (also
called bract/scale complex)
Young pine cone at pollination stage
os
b
Araucaria bidwillii seed cone
ovuliferous
scale
bract
one seed
per
ovuliferous
scale
Araucaria
angustifolia
Roasted and eaten
in Brazil
Araucaria
araucana
Monkey
Puzzle
Tree
Araucaria bidwillii
Bunya pine
Australia
pollen cones
Araucaria heterophylla
Cone-scale
complexes
Pollen cones
Seed cones
at pollination stage
Agathis (Araucariaceae)
Araucaria mirabilis
From the Cerro Cuadrado Petrified Forest, Patagonia
Jurassic
Taxodioid Cupressaceae
seed cones and
fossil casts
Metasequoia
Sequoiadendron
Taxodium
Pollen
cones
Cryptomeria
japonica
Seed cones
Cupressus
macrophylla
Cupressaceae
Thujopsis
Podocarpus
Podocarpaceae
Conifer pollination – Podocarpaceae
Microcachrys tetragona
Lagarostrobus colensoi
Podocarpus nivalis
Photos P.B. Tomlinson
Podocarpaceae
Prumnopitys
ladei
Retrophyllum
minor
New Caledonia
Dacrydium
Podocarpaceae
Rothwell et al. 2011
Ideas of conifer cone evolution from Rudolf Florin 1930’s-1964
Transformational series of the evolution of
the bract/scale complex in Cupressaceae
a. = Voltzia
b.= Cardiocarpidium
c. = Hughmillerites
d.= Taiwania
Taxodioid Cupressaceae-bract/scale complexes
development
Orange=seed/ovule, brown=bract, orange=ovuliferous scale, green=cone axis
(from Jagel 2001)
Evolution of the conifer seed cone
Ovuliferous scale of extant conifer cones evolved by the flattening
and reduction of a short shoot in a cordaitean-type plant, i.e., the ovuliferous
scale is homologous to a short shoot of a cordaitean.
Ideas of Rudolf Florin
1. Flattening of short shoot-radial to bilateral symmetry
2. Reduction in the number of scale leaves on the short
shoot,eventually to zero
3. Reduction in the number of ovules
4. Shortening of the cone axis =compaction of the cone
5. Shortening of the ovule stalk
6. Inversion of the ovule from orthotropous to anatropous
7. Fusion of the ovule stalk to the short shoot axis
Classostrobus
crossii
Rothwell, Mapes,
Hilton & Hollingworth
2007
Cheirolepidiaceae
Pollen cone
Classopollis
pollen
Pararaucaria patagonica
seed cone
Cheirolepidiaceae
Hirmeriella muensteri
Clement-Westerhof &
Van Konijnenburg-Van Cittert, 1991
Pararaucaria patagonica
Three Species of Pararaucaria
Argentina
Argentina
Oregon