Betulaceae

Alnus cordata

Italian alder

Look for: 
- Cordate leaf bases,
- slender male catkins,
- barrel-shaped female strobili.

- serrated margins

Betulaceae

Betula nigra

River birch

Look for: 
- One or more trunks with reddish-brown peeling bark [like paper] 
- leaves with doubly serrate margins,
- male and female catkins.

Betulaceae

Betula pendula

European white birch

Look for: 
- Smooth, white bark that breaks apart to show rougher gray patches underneath,

- bark is white and darker towards the base,
- thin branches that droop toward the ground,
- leaves with doubly serrate margins.

Fagaceae

Quercus agrifolia

Coast live oak

Look for: 
- Elliptic leaves that have spiny margins and are slightly cupped,
- axillary "armpit hair" where veins meet on backside of leaf,
- 4 to 5 pairs of secondary veins coming off the central leaf vein,
- bark that begins as a smooth, gray surface and splits apart to show rougher, darker areas as the trunk expands.

Fagaceae

Quercus ilex

Holly oak

Look for: 
- an evergreen tree with a single trunk and a dense canopy,
- elliptic to lanceolate leaves that are dark green above and white below,
- pinnate leaf venation with 10-12 pairs of secondary veins,
- irregular leaf margins that can be spiny, serrate, or entire, 
- cupules that partially cover the acorns,
- bark that matures from a smooth gray to a rough checkerboard ("alligator skin").

Fagaceae

Quercus lobata

Valley oak

Look for: 
- Deeply lobed simple leaves with no sharp points, 
- branches that arch up and then hang down almost vertically, 
- long, slender acorns.

Fagaceae

Quercus suber

Cork oak

Look for: 
- Live oak trees with thick, spongy bark, 
- shiny, simple, evergreen leaves with whitish undersides and spiny margins,
- acorn cupules that bristle outwards.

Flacourtiaceae

Xylosma congestum

Shiny xylosma

Look for: 
- a hedge, shrub, or small to medium-sized tree,
- shiny, alternate leaves with shallowly serrate margins and acuminate tips,
- pink petioles on the new growth,
- gray to white branches with prominent lenticels,
- (on the trees) a bending trunk covered in flat plates of yellow-gray bark .

Salicaceae

Populus nigra 'Italica'

Lombardy Poplar

Look for: 
- Tall, narrow trees,
- deltoid leaves with flattened petioles,

- truncated leaf base, 
- rough gray bark in vertical strips,
- branches around the tree all the way to the base (unless they've been pruned off).

Salicaceae

Populus tomentosa

Chinese white poplar

Look for: 
- Large, glossy leaves with rounded teeth and flattened petioles,
- white bark punctured by gray dots, 
- branches that are smooth, gray, and swollen at leaf nodes.

- leaves tomentose below in juvenile form 

Ulmaceae

Celtis occidentalis

Common hackberry

Look for:
- ovate, taper-pointed leaves that are oblique at base, glossy above, and hairy beneath,
- 3 main leaf veins that spread out from the leaf base,
- leaf margins that are smooth along the bottom third.

Ulmaceae

Celtis sinensis

Chinese hackberry

Look for: 
- A tree with rough, uneven, brown bark (often with patches of lichen), 
- ovate leaves with margins that change from entire to serrate around the midpoint, 
- solitary flowers that arise in the leaf axils, where each petiole meets the stem,
- solitary spherical fruits that ripen from green to reddish-orange in the fall.

Ulmaceae

Ulmus parvifolia

Chinese Elm

Look for: 
- Leaves with oblique bases and serrated margins, 
- abundant round, papery samaras,
- colorful bark that flakes off in puzzle pieces.

Ulmaceae

Ulmus americana

American Elm

Look for: 
- a trunk with rough, brown bark in vertical ribbons,
- alternate, simple leaves with doubly serrate margins, oblique bases, and sandpapery texture,
- fruits that are round, dry samaras.

Ulmaceae

Zelkova serrata

Japanese zelkova

Look for: 
- A medium-sized tree with a spherical canopy,
- bark that flakes off in flat "puzzle pieces," 
- narrow, elliptic leaves with pinnate venation, 
- a single row of rounded serrations on the leaf margins (not doubly serrate), 
- solitary fruits like "little green Hershey kisses" held in the leaf axils.