Download The Gymnosperms - Delaware Trees

The Gymnosperms
1. Probably the ancestors of all trees
2. “Naked Seeds,” usually formed on the scales of a cone
3. 4 Divisions within the Kingdom Plantae
• We cover Pinophyta (conifers) and Ginkgophyta (ginkgo)
The Gymnosperms
1. No true flowers
2. Reproductive morphology includes male and female cones
1. Male cones are smaller and produce pollen
2. Female cones are larger and produce seeds
3. Generally a tree will produce male and female cones
Together, the Gymnosperms
and the Angiosperms
comprise the seed plants.
Pinaceae: Genera Native to Delaware
1. Pinus (pine)
2. Tsuga (hemlock)
 At least some members of these genera are native
Pinaceae (the pine family)
• 10 genera with 200 species
• Northern hemisphere
• The most important family for timber production
• 6 genera are native to the U.S.
• Only 2 genera are native to Delaware
• All monoecious & wind-pollinated
• Woody cones
Pinaceae: Pinus (pines)
 More than 100 species worldwide, N hemisphere
 Whorled branches
 Leaves = needles in fascicles
 Male cones in spring, produce pollen
 Female cones develop later and are the “pine cones” we know
 Important products:
- lumber
- pulp and paper
- turpentine
- Christmas trees
- pine nuts
eastern white pine
Pinus strobus
• 5 needles per fascicle, needles have a bluish tinge
• Whorled branches like spokes on a wheel
• Dark gray, moderately furrowed bark with vertical ridges
• Cones 6” long, cylinder-shaped, with lots of resin
• Native only in the Piedmont in Delaware
• Inhabits moist, well-drained sites
• Intermediate shade tolerance
• Commercially valuable
loblolly pine
Pinus taeda
• 3 needles per fascicle, 6 to 9” long
• Cones <6”, oval, prickly spines
• Bark has distinctive texture with small vertical plates
• Good self-pruner
• Native to SE U.S. including DE Coastal Plain
• Found on a variety of habitats, also widely planted
• Provides nesting sites for birds, cover for deer & other wildlife
• Shade-intolerant pioneer species
• The mainstay of Delaware’s timber industry and the primary
timber tree of the southeastern U.S.
loblolly pine
Pinus taeda
• Regenerated by clearcutting or similar techniques
• Wood is used for pulp, paper, lumber, plywood, etc.
Loblolly pine
stands in Kent
and Sussex
Counties, DE
Virginia pine
Pinus virginiana
• 2 needles per fascicle that are short and twisted
• Cones are more round than loblolly cones
• Bark scaly, orange
• Usually crooked and poorly formed
• Small or medium-sized tree
• Native throughout Delaware
• Dry sites, shade intolerant
• Not commercially important here
pitch pine
Pinus rigida
• Similar to loblolly, except:
• needles are more stiff
• needles grow directly from the trunk in tufts
• cones are more round
• cones persist on the tree for many years
• Uncommon in Delaware
• Shade intolerant
• Dry sites (adapted to fire)
Cape Henlopen State Park
NJ Pine Barrens
Japanese black pine
Pinus thunbergii
• 2 needles per fascicle, about 5 inches long
• Cones oval, 3 inches long, not prickly
• Bark dark and rough
• Native to East Asia
• The predominant planted tree in some parts of
Sussex County, e.g. North Bethany
• Commonly planted throughout Delaware
•Affected by pinewood nematode causing a fatal disease
• Tolerant of poor sites
eastern hemlock
Tsuga canadensis
 Native to Delaware Piedmont (remnant Coastal Plain populations)
 Evergreen, needles only ½” long, not prickly
 Cones never more than 1” long
 Mature bark lightly furrowed, purple when cut
 Much troubled by hemlock wooly adelgid
 Native to NE USA, SE Canada, and down the Appalachians
 Inhabits moist woods
 Extremely shade-tolerant
 Some commercial and wildlife value
Tsuga canadensis
ginkgo
Ginkgo biloba (Ginkgoaceae)
• Leaves alternate, deciduous, fan-shaped with deep incision
• Palmate venation with many veins
• Leaves turn yellow and fall off almost overnight
• Fruit a modified cone, like a berry, smells bad
• Dioecious
• Ornamental
Ginkgo biloba