The identification tool Digiphyll – a short introduction

The identification tool of Digiphyll is based on check-boxes assigned to a number of leaf morphological characters (or traits). Individual leaf characters are defined systematically based on qualitative and quantitative properties (character states). These character states can be simply binary or hierarchically nested. The identification process in Digiphyll follows these levels via hierarchical check boxes: if the state of a leaf character is identified for the considered fossil, the corresponding check-box is clicked.

The cuticle is the waxy layer extruded by and covering the epidermis cells. This layer, when isolated and prepared, represents a cast of the epidermis and provides the appearance of the epidermis cells and the stomatal apparatus.
In the following, cuticle characters are divided into three groups.

C: characters of the adaxial cuticle (= upper leaf side)
D: characters of the mesophyll (leaf tissue)
E: characters of the abaxial cuticle (lower leaf side).

The character system used in Digiphyll follows vastly D. Dilcher (1974): Approaches to the identification of angiosperm leaf remains. - The Botanical Review, 40(1): 1–157. The concept of the identification process applied in Digiphyll will be summarised in the following. For a more detailed description of the traits, see Dilcher (1974).

C. Adaxial cuticle

All treated adaxial cuticle traits are split up into 13 sections. Each of these sections contains one or more characters with several character states:

C-1. Adaxial cuticle thickness

Describes the thickness of the cuticle, and is based upon sections and/or preparation, handling and general impression.

# Code Character State Description
1 C-1.1 delicate The cuticle thickness is rather delicate.
2 C-1.2 medium The cuticle thickness is medium.
3 C-1.3 thick The cuticle is thick.

C-2. Adaxial cuticle anticline

Describes the appearance of the anticlines.

# Code Character State Description
1 C-2.1 smooth The anticlines are even.
2 C-2.2 pitted The anticlines show regular or irregular thickenings.

C-3. Adaxial cuticle anticline-course

Describes the cell outline of the epidermis cells.

# Code Character State Description
1 C-3.1 straight The cells show straight outlines and angular corners.
2 C-3.2 rounded Cell outlines and corners are more or less rounded.
3 C-3.3 undulate The anticlines are wavy.
4 C-3.3.1 > U-shaped The undulation of the anticlines is U-shaped.
5 C-3.3.2 > V-shaped The undulation of the anticlines is V-shaped.
6 C-3.3.3 > Omega-shaped The undulation of the anticlines is shaped like an “Omega”.

C-4. Adaxial cuticle cell surface

Describes the surface profile of the epidermis cells.

# Code Character State Description
1 C-4.1 even The cell surface is even.
2 C-4.2 domed The cell surface is domed.
3 C-4.3 papillate The cell surface shows papillae.

C-5. Adaxial cuticle surface ornamentation

Describes presence and structure of epidermal cell surface ornamentations.

# Code Character State Description
1 C-5.1 smooth The surface is smooth – no structures present.
2 C-5.2 striate The surface shows narrow grooves.
3 C-5.3 wrinkled The surface shows wrinkles.
4 C-5.4 granular The surface has a granular appearance.

C-6. Adaxial cuticle trichome

Describes whether trichomes and glandular trichomes are present, and – if present – their arrangement and structure.

# Code Character State Description
1 C-6.1 absent No trichomes are present.
2 C-6.2 present Trichomes are visible.
3 C-6.2.1 > single Trichomes are not arranged in groups.
4 C-6.2.2 > in tufts Trichomes stand in groups, tightly arranged to each other.
5 C-6.2.3 > one-celled Trichomes consist of one cell only.
6 C-6.2.4 > pluri or multicellular Trichomes consist of more than one cell.

C-7. Adaxial cuticle trichome base

Describes the position of the trichome base relative to the epidermal surface.

# Code Character State Description
1 C-7.1 raised Trichome base is elevated above the cuticular surface.
2 C-7.2 at the epidemis level Trichome base is located at the level of the cuticular surface.
3 C-7.3 sunken Trichome base is sunken below the cuticular surface.

C-8. Adaxial cuticle trichome base cells

Describes the characters of the base cells of the trichomes.

# Code Character State Description
1 C-8.1 unmodified Base cells show no obvious modification.
2 C-8.2 modified Base cells show special features.
3 C-8.2.1 > thickened Base cells show thickened cell walls.
4 C-8.2.2 > unthickened Base cell walls as in other cells.
5 C-8.2.3 > radially elongated Base cells are radially elongated.
6 C-8.2.4 > radially not elongated Base cells are not radially elongated.

C-9. Adaxial cuticle trichome base poral rim

Describes the thickness of the rim around the base of the trichome.

# Code Character State Description
1 C-9.1 thickened Poral rim is thickened.
2 C-9.2 unthickened Poral rim is not thickened.

C-10. Adaxial cuticle trichome base foot

Describes the number of cells which compose the foot of the trichome base.

# Code Character State Description
1 C-10.1 one-celled Trichome base foot consists of one cell.
2 C-10.2 two-celled Trichome base foot consists of two cells.
3 C-10.3 more than two cells Trichome base foot consists of more than two cells.

C-11. Adaxial cuticle trichome stalk

Describes the number of cells which compose the stalk of the trichome.

# Code Character State Description
1 C-11.1 one-celled Trichome stalk consists of one cell.
2 C-11.2 two-celled Trichome stalk consists of two cells.
3 C-11.3 more than two cells Trichome stalk consists of more than two cells.

C-12. Adaxial cuticle trichome head

Describes the trichome head or tip.

# Code Character State Description
1 C-12.1 simple Trichome head is simple.
2 C-12.2 in tufts Trichome head forms a tuft.
3 C-12.3 one celled Trichome head consists of one cell only.
4 C-12.3.1 > linear (flagelliform) Trichome head cell has a linear shape.
5 C-12.3.1.1 >> short Trichome head cell is short (< 30µm).
6 C-12.3.1.2 >> medium Trichome head cell is medium long (30µm < x < 60µm).
7 C-12.3.1.3 >> long Trichome head cell is long (> 60µm).
8 C-12.3.2 > club-shaped Trichome head cell is club-shaped.
9 C-12.3.3 > globular Trichome head cell has a globular shape.
10 C-12.3.4 > peltate Trichome head cell is shield-shaped.
11 C-12.3.5 > other Trichome head cell has another shape.
12 C-12.4 pluricellular Trichome head consists of more than one cell.
13 C-12.4.1 > elongated Trichome head cells are elongated.
14 C-12.4.2 > club-shaped Trichome head cells are club-shaped.
15 C-12.4.3 > globular Trichome head cells have a globular shape.
16 C-12.4.4 > peltate Trichome head cells are shield-shaped.
17 C-12.4.5 > other Trichome head cells have another shape.

C-13. Adaxial cuticle epidermal secretory cells

Describes whether secretory cells are present in the epidermis.

# Code Character State Description
1 C-13.1 present Secretory cells are present.
2 C-13.2 absend Secretory cells are absent.

D. Mesophyll

Only one character is considered for the leaf ground tissue, the mesophyll.

D-1. Mesophyll secretory cells

Describes the absence/presence of secretory cells within the mesophyll, and their appearance.

# Code Character State Description
1 D-1.1 absent Secretory cells are absent.
2 D-1.2 present Secretory cells are present.
3 D-1.2.1 > sporadic Secretory cells occur sporadically.
4 D-1.2.1.1 >> shape globular Shape of secretory cells is globular.
5 D-1.2.1.2 >> elongated Shape of secretory cells is elongated.
6 D-1.2.1.3 >> irregular Shape of secretory cells is irregular.
7 D-1.2.2 > dense Density of secretory cells is high.
8 D-1.2.2.1 >> shape globular Shape of secretory cells is globular.
9 D-1.2.2.2 >> elongated Shape of secretory cells is elongated.
10 D-1.2.2.3 >> irregular Shape of secretory cells is irregular.

E. Abaxial cuticle

The abaxial cuticle characters are subdivided into 21 sections. Each of these sections contains one or more characters with several character states:

E-1. Abaxial cuticle thickness

Describes the thickness of the cuticle, and is based upon sections and/or preparation, handling and general impression.

# Code Character State Description
1 E-1.1 delicate The cuticle thickness is rather delicate.
2 E-1.2 medium The cuticle thickness is medium.
3 E-1.3 thick The cuticle is thick.

E-2. Abaxial cuticle anticline

Describes the appearance of the anticlines.

# Code Character State Description
1 E-2.1 smooth The anticlines are even.
2 E-2.2 pitted The anticlines show regular or irregular thickenings.

E-3. Abaxial cuticle anticline-course

Describes the cell outline of the epidermis cells.

# Code Character State Description
1 E-3.1 straight The cells show straight outlines and angular corners.
2 E-3.2 rounded Cell outlines and corners are more or less rounded.
3 E-3.3 undulate The anticlines are wavy.
4 E-3.3.1 > U-shaped The undulation of the anticlines is U-shaped.
5 E-3.3.2 > V-shaped The undulation of the anticlines is V-shaped.
6 E-3.3.3 > Omega-shaped The undulation of the anticlines is shaped like an “Omega”.

E-4. Abaxial cuticle cell surface

Describes the surface profile of the epidermis cells.

# Code Character State Description
1 E-4.1 even The cell surface is even.
2 E-4.2 domed The cell surface is domed.
3 E-4.3 papillate The cell surface shows papillae.

E-5. Abaxial cuticle surface ornamentation

Describes presence and structure of epidermal cell surface ornamentations.

# Code Character State Description
1 E-5.1 smooth The surface is smooth – no structures present.
2 E-5.2 stiate The surface shows narrow grooves.
3 E-5.3 wrinkled The surface shows wrinkles.
4 E-5.4 granular The surface has a granular appearance.

E-6. Abaxial cuticle trichome

Describes whether trichomes and glandular trichomes are present, and – if present – their arrangement and structure.

# Code Character State Description
1 E-6.1 absent No trichomes are present.
2 E-6.2 present Trichomes are visible.
3 E-6.2.1 > single Trichomes are not arranged in groups.
4 E-6.2.2 > in tufts Trichomes stand in groups, tightly arranged to each other.
5 E-6.2.3 > one-celled Trichomes consist of one cell only.
6 E-6.2.4 > pluri or multicellular Trichomes consist of more than one cell.

E-7. Abaxial cuticle trichome base

Describes the position of the trichome base relative to the epidermal surface.

# Code Character State Description
1 E-7.1 raised Trichome base is elevated above the cuticular surface.
2 E-7.2 at the epidemis level Trichome base is located at the level of the cuticular surface.
3 E-7.3 sunken Trichome base is sunken below the cuticular surface.

E-8. Abaxial cuticle trichome base cells

Describes characters of the base cells of the trichomes.

# Code Character State Description
1 E-8.1 unmodified Base cells show no obvious modification.
2 E-8.2 modified Base cells show special features.
3 E-8.2.1 > thickened Base cells show thickened cell walls.
4 E-8.2.2 > unthickened Base cell walls as in other cells.
5 E-8.2.3 > radially elongated Base cells are radially elongated.
6 E-8.2.4 > radially not elongated Base cells are not radially elongated.

E-9. Abaxial cuticle trichome base poral rim

Describes the thickness of the rim around the base of the trichome.

# Code Character State Description
1 E-9.1 thickened Poral rim is thickened.
2 E-9.2 unthickened Poral rim is not thickened.

E-10. Abaxial cuticle trichome base foot

Describes the number of cells which compose the foot of the trichome base.

# Code Character State Description
1 E-10.1 one-celled Trichome base foot consists of one cell.
2 E-10.2 two-celled Trichome base foot consists of two cells.
3 E-10.3 more than two cells Trichome base foot consists of more than two cells.

E-11. Abaxial cuticle trichome stalk

Describes the number of cells which compose the stalk of the trichome.

# Code Character State Description
1 E-11.1 one-celled Trichome stalk consists of one cell.
2 E-11.2 two-celled Trichome stalk consists of two cells.
3 E-11.3 more than two cells Trichome stalk consists of more than two cells.

E-12. Abaxial cuticle trichome head

Describes the trichome head or tip.

# Code Character State Description
1 E-12.1 simple Trichome head is simple.
2 E-12.2 in tufts Trichome head forms a tuft.
3 E-12.3 one celled Trichome head consists of one cell only.
4 E-12.3.1 > linear (flagelliform) Trichome head cell has a linear shape.
5 E-12.3.1.1 >> short Trichome head cell is short (< 30µm).
6 E-12.3.1.2 >> medium Trichome head cell is medium long (30µm < x < 60µm).
7 E-12.3.1.3 >> long Trichome head cell is long (> 60µm).
8 E-12.3.2 > club-shaped Trichome head cell is club-shaped.
9 E-12.3.3 > globular Trichome head cell has a globular shape.
10 E-12.3.4 > peltate Trichome head cell is shield-shaped.
11 E-12.3.5 > other Trichome head cell has another shape.
12 E-12.4 pluricellular Trichome head consists of more than one cell.
13 E-12.4.1 > elongated Trichome head cells are elongated.
14 E-12.4.2 > club-shaped Trichome head cells are club-shaped.
15 E-12.4.3 > globular Trichome head cells have a globular shape.
16 E-12.4.4 > peltate Trichome head cells are shield-shaped.
17 E-12.4.5 > other Trichome head cells have another shape.

E-13. Abaxial cuticle epidermal secretory cells

Describes whether secretory cells are present in the epidermis.

# Code Character State Description
1 E-13.1 present Secretory cells are present.
2 E-13.2 absend Secretory cells are absent.

E-14. Abaxial cuticle stomatal complex type

Describes the appearance and arrangement of epidermal cells adjacent to stomata.

# Code Character State Description
1 E-14.1 anomocytic Cells adjacent to the guard cells look like other epidermal cells.
2 E-14.2 anisocytic Stomata enclosed by 3 cells which may be unequal in size.
3 E-14.3 cyclocytic Stomata enclosed by a ring of small cells.
4 E-14.4 amphicyclocytic Stomata enclosed by a double ring of small cells.
5 E-14.5 actinocytic Stomata enclosed by a ring of larger or radially elongated cells.
6 E-14.6 paracytic Stomata enclosed by two or four cells.
7 E-14.7 brachyparacytic Stomata are flanked laterally by two cells.
8 E-14.8 paratetracytic Stomata enclosed by two elongated cells laterally and two polar cells.
9 E-14.9 anomotetracytic Stomata enclosed by four irregular cells.
10 E-14.10 other None of the patterns above.

E-15. Abaxial cuticle stoma orientation

Describes the orientation of the stomata with respect to the long axis of the leaf.

# Code Character State Description
1 E-15.1 random Stomata are arranged randomly.
2 E-15.2 sub-parallel Stomata are arranged almost parallel to each other.
3 E-15.3 parallel The long axis of stomata oriented parallel to the long axis of the leaf.

E-16. Abaxial cuticle stoma distribution

Describes whether stomata are arranged in groups or not.

# Code Character State Description
1 E-16.1 ungrouped Stomata are single, not grouped.
2 E-16.2 grouped Stomata are arranged in groups.

E-17. Abaxial cuticle stoma position relative to epidermis

Describes whether stomata are raised, sunken or at the same level of the epidermis.

# Code Character State Description
1 E-17.1 raised Stomata are raised above epidermis level.
2 E-17.2 at the epidermis level Stomata are at the same level of the epidermis.
3 E-17.3 sunken Stomata are sunken below the epidermis.

E-18. Abaxial cuticle stoma shape

Describes the shape of the stomata.

# Code Character State Description
1 E-18.1 roundish The stomata have a roundish appearance.
2 E-18.2 elliptic The stomata have an elliptic shape.

E-19. Abaxial cuticle guard cells

Describes the appearance of the guard cells.

# Code Character State Description
1 E-19.1 without polar thickenings The guard cells do not show thickenings at their poles.
2 E-19.2 with polar thickenings The guard cells show polar thickenings.
3 E-19.2.1 > I-shaped Polar thickenings are I-shaped.
4 E-19.2.2 > T-shaped Polar thickenings are T-shaped.

E-20. Abaxial cuticle stomatal ledges

Describes whether stomatal ledges have a distinct appearance by strong cutinization.

# Code Character State Description
1 E-20.1 weakly cutinised Stomatal ledges are weakly cutinized and therefore unconspicuous.
2 E-20.2 conspicuous Stomatal ledges are strongly cutinized and therefore distinct.

E-21. Abaxial cuticle front cavity

Describes the appearance of the front cavity of the stomata.

# Code Character State Description
1 E-21.1 roundish Front cavities are roundish.
2 E-21.2 elliptic Front cavities are elliptic.
3 E-21.3 spindle-shaped Front cavities are spindle-shaped.