Distinct areas of the pollen grain surface may show different ornamentation types

The type of ornamentation may be irregularly distributed over the pollen surface, or restricted to distinct surface regions.

Some examples may elucidate this feature:

— The polar region of Fallopia convolvulus is psilate to perforate, apertural regions are microechinate.

■ In Sideritis montana polar and inter-apertural areas are perforate to fove-olate, apertural regions are psilate.

■ In Salvia austriaca the polar area is psilate to perforate, all other areas being bireticulate.

■ Solandra longiflora is an example where the polar areas are reticulate, while in equatorial view the ornamentation is striato-reticulate.

Combination of ornamenting characters left:

Fallopia convolvulus Polygonaceae polar view right:

Sideritis montana Lamiaceae polar view

Salvia austriaca Lamiaceae left: polar view right: equatorial view

Solandra longiflora Solanaceae left: polar view right: equatorial view

Combination of ornamenting characters left:

Fallopia convolvulus Polygonaceae polar view right:

Sideritis montana Lamiaceae polar view

Salvia austriaca Lamiaceae left: polar view right: equatorial view

Solandra longiflora Solanaceae left: polar view right: equatorial view

Interpretation of ornamenting characters

Sanchezia nobilis Acanthaceae oblique equatorial view surface detail

Interpretation of ornamenting characters

Sanchezia nobilis Acanthaceae oblique equatorial view surface detail

Sometimes it depends on the individual researcher to interpret ornamenting features: for example, to call Sanchezia nobilis (Acanthaceae) plicate and striate, but also reticulate? And should the rod-like elements be termed clavae, or free-standing columellae? Moreover, is the aperture to be interpreted as a porus or a colporus?

A special case deserves attention. In heterostylous species two different pollen types occur. Size and number of apertures, e.g., in Primula, or the ornamentation e.g., in Linum, may differ.

For better illustration Linum flavum and Primula pollen of the two floral types (long-styled and short-styled, pin and thrum morphs) is shown here.

In Linum flavum the short-styled-morph pollen is baculate, and the long-styled-morph clavate.

In Primula veris the pollen of the short-styled morph (thrum) is larger and has more apertures than the pollen of the long-styled morph (pin).

Heterostyly

Linum flavum Linaceae short-styled morph baculate long-styled morph clavate

Heterostyly

Linum flavum Linaceae short-styled morph baculate long-styled morph clavate

Heterostyly

Primula veris Primulaceae left:

short-styled morph right: long-styled morph

Heterostyly

Primula veris Primulaceae left:

short-styled morph right: long-styled morph

Was this article helpful?

0 0

Post a comment