Discussion in relation to previous studies

A comprehensive wood anatomical study was performed by Richter (1981) in which he described the xylem and the phloem of 180 genera with 830 tree species. Schweingruber (1990) described the xylem of Laurus nobilis, L. azorica, Persea indica and Ocotea foetens. Gregory (1994) mentions further 190 references about the wood anatomy of mainly tropical Lau-raceae.

The present study describes a few species occurring in Western Europe and on the Canary Islands, but it is far from representative for the whole family. Most representative for all Lauraceae species is the presence of paratracheal parenchyma and the occurence of alternating intervessel pits is a key feature of Lauraceae (Richter 1981).

Present features in relation to the number of analyzed species

62

fiber pits large and distinctly bordered

IAWA code frequency

(>3 pm = fiber tracheids)

1

Total number of species

6

septate fibers present

3

1

growth rings distinct and recognizable

4

70

fibers thin- to thick-walled

6

2

growth rings indistinct or absent

2

70.2

tension wood present

3

4

semi-ring-porous

1

76

parenchyma apotracheal, diffuse and in aggregates

3

S

diffuse-porous

4

79

parenchyma paratracheal

3

9

vessels predominantly solitary

3

97

rays width predominantly 1-3 cells

S

9.1

vessels in radial multiples of 2-4 common

6

98

rays commonly 4-10-seriate

2

11

vessels predominantly in clusters

1

100.2

rays not visible in polarized light

1

13

vessels with simple perforation plates

S

10î

ray: all cells upright or square

3

14

vessels with scalariform perforation plates

1

106

ray: heterocellular with 1 upright cell row (radial section) 3

21

intervessel pits opposite

1

107

ray: heterocellular with 2-4 upright cell rows

31

vessel-ray pits with large apertures, Salix/Laurus type

4

(radial section)

3

32

vessel-ray pits with large horizontal apertures,

108

ray: heterocellular with >4 upright cell rows

Hamamelidaceae type

1

(radial section)

1

36

helical thickenings present

1

110

rays with sheet cells (tangential section)

1

41

earlywood vessels: tangential diameter 50-100 pm

2

124

oil and mucilage cells

3

42

earlywood vessels: tangential diameter 100-200 pm

S

136

prismatic crystals present

3

Í0

<100 vessels per mm2 in earlywood

S

R3

distinct ray dilatations

3

Î0.1

100-200 vessels per mm2 in earlywood

1

R4

sclereids in phloem and cortex

S

Í6

tylosis with thin walls common

3

R7

with prismatic crystals

4

Í8

dark-stained substances in vessels

R9

with crystal sand

1

and/or fibers present (gum, tannins)

1

R12

with laticifers, oil ducts or mucilage ducts

2

61

fiber pits small and simple to minutely bordered (<3 pm = libriform fibers)

S

P2

with laticifers or intercellular canals

1

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