The Gymnosperms

1. The Gymnosperms • Probably the ancestors of all trees • “Naked Seeds,” usually formed on the scales of a cone • 4 Divisions within the Kingdom Plantae • We cover Pinophyta (conifers) and Ginkgophyta (ginkgo)

2. The Gymnosperms • No true flowers • Reproductive morphology includes male and female cones • Male cones are smaller and produce pollen • Female cones are larger and produce seeds • Generally a tree will produce male and female cones

3. Together, the Gymnosperms and the Angiosperms comprise the seed plants.

4. Pinaceae: Genera Native to Delaware • Pinus (pine) • Tsuga (hemlock)  At least some members of these genera are native

5. 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

6. 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

7. 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

8. 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.

9. loblolly pine Pinus taeda Loblolly pine stands in Kent and Sussex Counties, DE • Regenerated by clearcutting or similar techniques • Wood is used for pulp, paper, lumber, plywood, etc.

10. 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

11. 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

12. 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

13. 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

14. Tsuga canadensis

15. 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

16. Ginkgo biloba