Sorbus- Mountain Ash

Question 1

Sorbus

Answer 1

Mountain Ash

Question 2

Sorbus- characteristics

Answer 2

75 species worldwide
4 native to canada
commonly grown for their ornamental features and bright persistent fruit
bark has elongated lenticels
fruit is an important source of food for wildlife especially in winter
all have alternate bud formation

Question 3

Two common species grown here; will easily hybridize

Answer 3

Sorbus decora
Sorbus aucuparia

Question 4

Sorbus decora

Answer 4

smaller tree but overall a bit more showy
tends to be multi-trunked

Question 5

Sorbus aucuparia

Answer 5

largest of the mountain ash here
can be single trunk or mutli-trunked

Question 6

Mountain ash colouration

Answer 6

autumn colouration showy yellow to burgundy

Question 7

Sorbus- leaf

Answer 7

variable leaf shape, partly due to hybridization between species
can find variation within tree; look at majority of leaves not just one leaf

Question 8

Sorbus aucuparia- leaves

Answer 8

usually entire on lower third/quarter of leaflets
rachis often red tinged
oblong to oblong-lanceolate leaflets
9-15 leaflets
leafy stipules
stipules can be quite large
leaflets sessily or nearly sessile
blunt/short tipped at apex
rounded base; oblique possible

Question 9

Sorbus aucupuria- bud

Answer 9

brown bud but white very pubescent covering

Question 10

Sorbus decora- leaf

Answer 10

oblong to lanceolate-oblong
abruptly acute to obtuse at the apex
rounded at base; oblique possible
short petiolule/usually not sessile
13-17 leaflets
margins usually sharply serrate

Question 11

Variation in bark colour- new growth

Answer 11

Sorbus aucuparia often bronzy
sorbus decora more reddish

Question 12

Variation in bark colour- old growth

Answer 12

Sorbus aucuparia often coppery brown bark
Sorbus decora often has grayer bark

Question 13

Sorbus flowers

Answer 13

white showy flowers on all species; flat topped corymb

Question 14

Variation in fruit colour and size

Answer 14

Sorbus aucuparia- orange and smaller
sorbus decora- red and larger

Question 15

Less common hybrids

Answer 15

columnar mountain ash
columnar oakleaf mountain ash
Sorbus x hybrida ‘Fastigiata’