D³ database

Diaspore Morphology

Summary

 

DIASPORE MORPHOLOGY describes morphology, appendages and structure of diaspores (which may be the whole plant, infructescences, compound fruits, fruits, fruit segments or seeds, often with additional structures). In D³ DIASPORE MORPHOLOGY is technically treated as a bundle of binary traits in order to describe multiple categories of DIASPORE MORPHOLOGY which often can be found on one single diaspore (e.g. Fig. 1).

Additionally, we present a Morphology Code describing the diaspore morphology shortly.

 

 

Trait description

 

DIASPORE MORPHOLOGY describes morphology, appendages and structure of diaspores in respect to seed dispersal. It is coded in several binary variables as listed in Tab. 1. Each morphological structure that appears in the diaspores of a species is coded with '1' in the respective variable whereas '0' means that this feature is not applicable in this species.

In order to minimize the number of binary traits, we only present the main hierarchical level in the online version of the database.

The complete information on the diaspore morphology is available in a compact formula in the field Morphology Code (DIA_MORPH) which includes the information on diaspore typology and the numeric codes from Tab. 1. In case of heterodiaspory the morphology codes of additional diaspore types are listed in a 'comment' field. Furthermore, in case of heterodiaspory with two morphological identical diaspores, the morphology codes are consecutively numbered.

 

 

Tab. 1. Categorization of DIASPORE MORPHOLOGY

No.

Variable name

Description

Examples

1

NUTRIENTS

The diaspore contains a significant amount of nutrients, either in quantity (typically large diaspores) or in quality (e.g. fruits with extraordinary high levels of fatty acids, proteins or other nutrients).

This category is only used if it is not possible to address the subordinate hierarchical level.

1a

nutrient-rich envelope

The nutrient-containing structure encloses the seeds. While on purpose typically only the fruit flesh is fed, seeds may be dispersed if they are spit or if they are fed (accidentally) and survive digestion.

 

E.g. Sorbus, Rubus, Prunus

Prunus spinosa - drupes.

1b

nutrient-containing appendage

Diaspores with nutrient-rich appendages, which can often be separated easily from the seed (e.g. aril, elaiosome). Typically the seeds are dispersed without being digested.

 

E.g. Euphorbia with elaiosome, Taxus with aril

 Viola palustris - brown seed with white elaiosome.

1c

nutrient rich seed

The nutrients are stored in the seed. That means utilisation of the nutrients by seed dispersing animals (endozoo- or dysochory) is intrinsically related to severe damage or death of the embryo.

 

E.g. Fagus or Castanea with high quantities of nutrients, and most Poaceae (due to the aleuron layer) and many Fabaceae (due to the high nitrogen contents) with a high quality of nutrients.

Quercus robur - nutrient-rich nuts.

2

AERENCHYM

Aerenchyms favour the adherence of air to the diaspore. Air is +/- enclosed in the tissue or by hull-structures and cannot leak. Aerenchyms decrease the effective density of the diaspore and may promote dispersal by water or wind.

 

E.g. Carex (and other Cyperaceae), Nymphaea alba, Menyanthes trifoliata

Carex vesicaria - top view on a diaspore (left) and longitudinal section (right) showing the air-filled space between the small fruit (with a long stylus) and the utricle which forms the hull.

3

WINGS

Flat, thin appendages (wings, perianths, bracts etc.) which stick out of the more compact part of the diaspore that contains the embryo. Wings typically enhance wind dispersal.

 

E.g. Acer, Betula, Fraxinus, Tilia, many Pinaceae

Pinus mugo - seed with wing.

4

ELONGATED

All structures that prominently elongate the main body of the diaspore, which contains the embryo.

This category is only used if it is not possible to address the subordinate hierarchical level.

4a

one short appendage

One short appendage.

Ranunculus repens - The style is classified as one short appendage.

4b

many short appendages

More than one short appendage (e.g. short hairs).

Bromus intermedius - The short hairs are classified as many short appendages.

4c

one long appendage

One long appendage (e.g. an awn).

 

E.g. Geum, Pulsatilla, many Poaceae with awns

Bromus intermedius - The awn is classified as one long appendage.

4d

many long appendages

More than one long appendage (e.g. pappus or long hairs) could enhance anemo- and epizoochory.

 

E.g. Taraxacum, Arnica, Centaurea

Arnica montana - The pappus hairs are classified as many long appendages.

5

HOOKED

Appendages with hooks or other structures which imply adhesion, except glueing substances.

 

E.g. Agrimonia, Arctium, some Bidens species

 Agrimonia repens - diaspore with many hooked appendages.

6

MUCILAGINOUS

Diaspores with a mucilaginous surface.

In many species the diaspore becomes mucilaginous only if the diaspores become wet. This phenomenon is little studied and its function still unclear. The sticky surface may enhance adhesion which can inhibit long distance dispersal (ateleochory) but also enhance epizoochory. Furthermore, seeds could be protected against digestion.

 

E.g. many Anthemideae, Brassicaceae, Salvia pratensis

Salvia pratensis - Dry fruit segments (left) are not mucilaginous, whereas wetted segments develop a mucilaginous coat within short time (right).

7

NO SPECIALIZATIONS

Diaspores without any of the above mentioned (or other) specializations.

This category is only used if it is not possible to address the subordinate hierarchical level.

7a

coarse surface

Diaspores with a structured surface and no further appendages or specializations.

 

E.g. many Caryophyllaceae

Silene vulgaris - seed with a coarse surface.

7b

smooth surface

Diaspores with a smooth surface and no further appendages or specializations.

 

E.g. many Brassicaceae

Brassica oleraceae ssp. oleraceae - seeds with a smooth surface.

8

OTHER SPECIALIZATIONS

Reserved for specialized vegetative parts.

Poa bulbosa - The spikelets are transformed into vegetatively produced bulbils, which rapidly start their development (pseudovivipary).

 

 

A short example (Fig. 1) illustrates the classification of multiple appendages: Using the compact formula, the Morphology Code of the diaspore of Helictotrichon versicolor is described as fruit|1c.3.4b.4c.5| in the field DIA_MORPH.

 

 Fig. 1. The diaspore of the Poaceae Helictotrichon versicolor is typically a single floret, i.e. a fruit (with additional structures: the glumes and the callus). The diaspore shows several adaptations that may be related to seed dispersal: The seeds contain valuable nutrients, especially proteins and vitamins in the aleuron-layer and starch in the large endosperm. The diaspore is therefore categorized as having a nutrient-rich seed (No. 1c in Tab.1). The glumes are wing-like and classified as flat appendages (No. 3 in Tab.1). The callus has many fine hairs, which are addressed as many short elongated appendages (No. 4b in Tab.1), and the lemma has a long awn, which is classified as one long elongated appendage (No. 4c in Tab.1). The whole diaspore may act as a hook (No. 5 in Tab.1), especially the geniculate awn in combination with the stiff callus hairs.

 

 

Data sources

 

The used categorization scheme was inspired by the LEDA approach (Römermann et al., 2005) but significantly modified, so that the classification was done independently from the LEDA approach for all species. DIASPORE MORPHOLOGY therefore represents a new original dataset, which was derived from visual inspection of the diaspores or respective images and an intensive literature and web research.

 

 

Selected literature

 

Bojňanský, V. & Fargašová, A. (2007): Atlas of seeds and fruits of Central and East-European flora. The Carpathian Mountains region. Springer, Dordrecht.

 

Cappers, R.T.J., Bekker, R.M. & Jans, J.E.A. (2006): Digital Seed Atlas of the Netherlands. Barkhuis.

 

Graf, J. et al. (1987): Tafelwerk zur Pflanzensystematik. Einführung in das natürliche System der Blütenpflanzen. Springer-Verlag.

 

Hegi, G. (1908ff): Illustrierte Flora von Mittel-Europa. Mit besonderer Berücksichtigung von Deutschland, Oesterreich und der Schweiz. Zahlreiche Bände in drei Auflagen. J. F. Lehmanns Verlag, 2. und 3. Auflage bei Paul Parey und Weissdorn-Verlag.

 

Hilger, H.H. & Hoppe, J.R. (1995): Die morphologische Vielfalt der generativen Diasporen – Präsentation eines Lehr- und Lernschemas. Feddes Repertorium 106, 503-513.

 

Otto, B. (2002): Merkmale von Samen, Früchten, generativen Germinulen und generativen Diasporen. In: Klotz, S., Kühn, I. & Durka, W. [Hrsg.] (2002): BIOLFLOR - Eine Datenbank zu biologisch-ökologischen Merkmalen der Gefäßpflanzen in Deutschland. - Schriftenreihe für Vegetationskunde 38, Bonn: Bundesamt für Naturschutz, 177-196.

 

Römermann, C., Götzenberger, L., Tackenberg, O. & Poschlod, P. (2005): Morphology of dispersal unit. In: Knevel, I.C., Bekker, R.M., Kunzmann, D., Stadler, M., Thompson, K. (eds.): The LEDA traitbase collecting and measuring standards.