Download Rosaceae

Rosaceae
Crataegus sp. – Hawthorns
Hawthorns are a large genus
(~200 sp.) native to North
America, Europe and Asia.
They have long been
cultivated for their edible
fruit and as ornamentals.
Many are armed with large
thorns.
Rosaceae
Crataegus sp. – Hawthorns
There is a considerable amount of European folklore surrounding hawthorns.
They are a collection of large shrubs and small trees attractive in flower and fruit.
Rosaceae
Crataegus sp. – Hawthorns
The genus name is from the
Greek word kratos for
“strength” an indication of the
hardness of the wood.
Although cultivated hawthorns
have multi-season ornamental
appeal, they are susceptible to
numerous insect and disease
problems.
Rosaceae
Crataegus sp. – Hawthorns
Hawthorns are susceptible to both Cedar-apple rust and Cedar-hawthorn
rust. Galls produced by cedar-hawthorn rust (G. globosum) are similar in
appearance to cedar-apple rust, but are smaller and more irregular in shape.
Spore horns, too, are shorter, generally fewer in number, and wedge- or clubshaped. Click here for more information on rust diseases.
Leaf
infection
Gall forming
in flowers
Infected
fruit
Rosaceae
Crataegus sp. – Hawthorns
Cedar hawthorn rust
is a disease where the
pathogen completes
part of its life cycle
on hawthorn and part
on juniper.
White-orange “spore horns”
protruding from hawthorn fruit
releasing spores in the fall.
Yellow-orange “spore horns”
protruding from a cedar gall
on J. virginiana releasing
spores in the spring.
Rosaceae
Crataegus sp. – Hawthorns
In addition to rust, hawthorns
are susceptible to numerous
diseases including leaf spots,
scab, and fireblight.
Rosaceae
Crataegus sp. – Hawthorns
Hawthorns are the host for a variety
of insects including tent caterpillars,
leaf miners, lacebugs and mites.
Apple leaf
blotch miner
Rosaceae
Crataegus sp. – Hawthorns
Lace bugs can be very damaging to hawthorn
leaves and can occur in high populations.
Immature
Adults
Adult and immature lace bugs on the
underside of a hawthorn leaf.
Rosaceae
Crataegus crusgalli – Cockspur hawthorn
Cockspur hawthorn is a
versatile plant that can be
grown as a single specimen,
in groups with other small
trees, or as a barrier hedge.
It is native to Eastern
North America from Canada
to North Carolina, west to
Kansas.
Rosaceae
Crataegus crusgalli – Cockspur hawthorn
Growth habit – Forms a lowbranching small tree with a
dense spreading crown.
Thorny branches form an
impenetrable cover.
Tree size – Can reach 30 feet
tall with a 20 foot spread.
Rosaceae
Crataegus crusgalli – Cockspur hawthorn
Flower and fruit – Small white, fivepetaled flowers appear in May in flat
corymbs. They are showy for only a
brief time.
Fruits are red pomes and are effective
into the winter.
Rosaceae
Crataegus crusgalli – Cockspur hawthorn
Leaf – Simple, obovate leaves with
an alternate arrangement.
Leaf margin sharply serrate.
Reddish-purple autumn color.
Rosaceae
Crataegus crusgalli – Cockspur hawthorn
Stems – Stems have un-branched thorns.
Thick branching makes good wildlife
habitat. The sharp thorns make this plant
not kid or pedestrian friendly.
Rosaceae
Crataegus crusgalli – Cockspur hawthorn
Culture:
Full sun.
Tolerant of most landscape
situations as long as the soil is
well-drained.
Susceptible to rust.
Hardy in zones 7 to 4.
Pruning makes the plants very
dense and fiercely impregnable
to human or animal traffic.
Rosaceae
Crataegus crusgalli – Cockspur hawthorn
Uses: Cockspur hawthorn tolerates pruning and can make an interesting hedge.
Rosaceae
Crataegus crusgalli – Cockspur hawthorn
Cultivars:
There are thornless selections
of cockspur hawthorn available
as C. crusgalli var. inermis.
Crusader (‘Cruzam’) is marketed
as a thornless type.
Rosaceae
Crataegus xlavalleei – Lavalle hawthorn
Lavalle hawthorn is a hybrid
between Crataegus crusgalli
and Crataegus mexicana.
It is usually used as a small
specimen tree.
It shows good rust tolerance.
Rosaceae
Crataegus xlavalleei – Lavalle hawthorn
Growth habit – An irregular
to round crown. It often
shows more growth on one
side of the tree than the
other.
Tree size – Can reach 20
feet tall and wide.
Rosaceae
Crataegus xlavalleei – Lavalle hawthorn
Flower – Small white flowers
appear in late May in flat corymbs.
Rosaceae
Crataegus xlavalleei – Lavalle hawthorn
Fruit – Fruits are relatively large
orange-red pomes with brown spots.
Rosaceae
Crataegus xlavalleei – Lavalle hawthorn
Leaf – Leaves are simple, alternate
with a serrate margin on the upper
two-thirds of the leaf.
Coppery-red autumn color.
Plants have short un-branched
thorns.
Rosaceae
Crataegus xlavalleei – Lavalle hawthorn
Culture:
Full sun.
An easily grown hawthorn
adaptable to most landscape
conditions.
Resistant to the rust disease
that infects other hawthorns,
but susceptible to lace bug.
Hardy in zones 7 to 4.
Lace bug damage
Rosaceae
Crataegus viridis ‘Winter King’ – Winter King green hawthorn
Winter King is the only green
hawthorn used in the landscape.
It is small tree useful as a single
specimen or in small groups.
This is the best of the landscape
hawthorns for growth habit,
ornamental flowers and fruits.
Native to Eastern North
America.
Rosaceae
Crataegus viridis ‘Winter King’ – Winter King green hawthorn
Growth habit – A small,
vase-shaped tree becoming
rounded with age.
Tree size – Usually grows to
approximately 25 feet tall
and wide, but can reach 50
feet tall.
Rosaceae
Crataegus viridis ‘Winter King’ – Winter King green hawthorn
Flowers – Small white flowers in
corymbs appear in May as the
foliage emerges. Flowers have 20
yellow stamens.
Rosaceae
Crataegus viridis ‘Winter King’ – Winter King green hawthorn
Fruit – Fruits are bright red,
small pomes.
Winter King fruit are larger
than the species.
Fruit persists into winter.
Rosaceae
Crataegus viridis ‘Winter King’ – Winter King green hawthorn
Leaf – Simple, alternate with a
serrated leaf margin. The upper portion
of the leaf can have shallow lobes.
Plants can have good yellow to red
autumn color.
Rosaceae
Crataegus viridis ‘Winter King’ – Winter King green hawthorn
Thorns – Winter King green
hawthorn produces sporadic thorns.
The thorns are fewer and shorter
than those of cockspur hawthorn
(Crataegus crusgalli ) and
Washington hawthorn (Crataegus
phaenopyrum).
Rosaceae
Crataegus viridis ‘Winter King’ – Winter King green hawthorn
Culture:
Full sun.
An easily grown hawthorn that is
tolerant of most landscape sites.
Susceptible to rust, but still
provides a good fruit display.
One of the best hawthorns.
Hardy in zones 7 to 4.
Rosaceae
Crataegus viridis ‘Winter King’ – Winter King green hawthorn
Use:
Winter green hawthorn is
an excellent small tree
for commercial and
residential landscapes.
Rosaceae
Cotoneaster
Cotoneaster is a large genus with
between 70 and 300+ species
depending on the reference
making nomenclature and
identification can be difficult.
They are generally most
ornamental while in fruit.
They can be short-lived especially
where summers are hot and humid
where they are very susceptible
to mites, lacebug and fireblight.
The genus name is Latin for
cotoneum (quince) and aster
(similar to).
Cotoneaster lacteus
Rosaceae
Cotoneaster dammeri – Bearberry cotoneaster
Bearberry cotoneaster is a
low-growing evergreen
groundcover. Useful in
mass or mixed with other
groundcovers and shrubs.
Grows quickly to cover an
area, but can become
unkempt with age without
timely pruning.
Native to Central China.
The genus name is Latin
for cotoneum (quince) and
aster (similar to).
Rosaceae
Cotoneaster dammeri – Bearberry cotoneaster
Growth habit – A spreading
groundcover with low arching
branches.
Grows to about 2 feet tall and
spreads over 6 feet.
Renewal pruning is required to
keep plants compact with age.
Rosaceae
Cotoneaster dammeri – Bearberry cotoneaster
Flower and fruit – Small, white
five petal flowers appear in
the spring. Flowers are
solitary or produced in pairs.
Not very showy.
Fruits are small globose red
pomes that are effective if
produced in enough numbers.
Rosaceae
Cotoneaster dammeri – Bearberry cotoneaster
Leaf – Small (~ 1 inch long), elliptic
shaped, alternate and simple.
Semi-evergreen in Kentucky.
Rosaceae
Cotoneaster dammeri – Bearberry cotoneaster
Culture:
Full sun.
An easy shrub to grow as it
tolerates most landscapes
site as long as they are not
overly wet.
Hardy in zones 7 to 5.
Rosaceae
Cotoneaster dammeri – Bearberry cotoneaster
Culture:
The usefulness of cotoneasters as
landscape plants is limited by their
susceptibility to fireblight, mites and
lacebug. These problems are more
severe in the southeastern states.
Mites
Lacebug
Rosaceae
Cotoneaster dammeri – Bearberry cotoneaster
Cultivars:
‘Skogholm’ is the most commonly planted
cultivar because of its vigorous, low growth.
Rosaceae
Cotoneaster dammeri – Bearberry cotoneaster
Cultivars:
‘Lowfast’ grows to about one foot
tall with glossy green foliage.
Rosaceae
Cotoneaster horizontalis – Rockspray cotoneaster
Rockspray cotoneaster is
a good groundcover
massed or mixed with
other similar plants.
Plant on a slope to take
advantage of the arching
branches.
Native to Northern Asia
– Siberia.
Rosaceae
Cotoneaster horizontalis – Rockspray cotoneaster
Growth habit – A dense,
low-growing shrub with a
herringbone branching
habit.
Arching stems grow to 3
feet tall and 6 or more
feet wide.
Branches root where they
hit the soil to allow plants
to spread.
Rosaceae
Cotoneaster horizontalis – Rockspray cotoneaster
Flower – Flowers are small,
perfect pink flowers that are
not very showy. They are usually
solitary on very short pedicels.
Rosaceae
Cotoneaster horizontalis – Rockspray cotoneaster
Fruit – Fruit is a small, red pome.
Rosaceae
Cotoneaster horizontalis – Rockspray cotoneaster
Leaf – Leaves are alternate, broadly
elliptical and about one-half inch long.
Semi-evergreen. Autumn color is a
reddish - purple.
Rosaceae
Cotoneaster horizontalis – Rockspray cotoneaster
Stems – One of the recognizable
attributes of rockspray
cotoneaster is that the side
branches come off the main stem
in a “herringbone” pattern.
Rosaceae
Cotoneaster horizontalis – Rockspray cotoneaster
Culture:
Full sun or partial shade.
An easily grown plant that
is tolerant of most
landscape situations.
Prune to keep from
becoming too open.
Susceptible to mites and
lacebug.
Hardy in zones 7 to 5.
Rosaceae
Cotoneaster horizontalis – Rockspray cotoneaster
Cultivars:
‘Hessei’ produces tightly
branched plants that curve
downward to produce a
pendulous effect.
It is probably a hybrid
between C. horizontalis and
C. apiculatus.
Rosaceae
Cotoneaster horizontalis – Rockspray cotoneaster
Cultivars: ‘Robusta’ plants are more upright and
vigorous with good fruit set.
Rosaceae
Cotoneaster horizontalis – Rockspray cotoneaster
Cultivars:
‘Tom Thumb’ is a slower growing
densely branched form.
It is fairly common in the nursery
trade, but can be sold under C.
horizontalis as ‘Tom Thumb’ or as
C. adpressus ‘Little Gem’.
This is not unexpected because
some taxonomists consider
C. adpressus to be a botanical
variety of C. horizontalis.
Rosaceae
Cotoneaster horizontalis – Rockspray cotoneaster
Cultivars: ‘Variegatus’ is a green and white form with smaller leaves.