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The Geometry of Pollen

Wikipedia tells us that “Pollen is a fine to coarse powdery substance comprising pollen grains which are male microgametophytes of seed plants, which produce male gametes (sperm cells).”

As Peter Calamai writes, “So small, so vital, so beautiful.  And so very sexy.  That pretty much sums up pollen.”

Individual pollen grains are small enough to require magnification to see detail.

The book Pollen: The Hidden Sexuality of Flowers by Rob Kesseler & Madeline Harley is essential to view the extraordinary microscopic detail of these beautiful tiny works of art.  A sampling is shown in this article.


Pollen emerges from the anthers of stamens.  “In its activity,” writes Goethe, “this pollen replaces the expansive force taken from the vessels which produced it.  Now released, it seeks out the female parts that the same effect of nature brings to meet it; it attaches itself to these parts, and suffuses them with its influence…The fine matter developed in the anthers looks like a powder, but these tiny grains of pollen are just vessels containing a highly refined juice.”

Pollen attached to anthers.  The anthers are the six brown parts attached to the end of the stamens.


There is an astonishing diversity of pollen grains and thousands of pollen types.  Their size ranges from 5-250 microns.  Most are between 20 and 80 microns.


“They are tiny – perfect masterpieces of natural architecture and structural engineering – and often breathtakingly beautiful.”1

Passionflower, Peace Lily & Daisy Pollen


Pollen is an important symbol in the Navajo belief system.

“Pollen is one of the most important ritual symbols that serve as a bridge between belief and action in the sandpainting ceremony.  The strewing of pollen is the final ritual act that blesses the sandpainting; the expansiveness of this gesture as well as the pollen itself animate the sandpainting with life.

Gladys Reichard equated pollen with light by saying, ‘Light is an essential of life and protection, whose most outstanding symbol is pollen.  It emits light in all directions, it shines in amongst.’  Since light [sunbeams, warmth] is a necessary element of generation, it is not surprising that pollen should be the symbol of fructification, vivification, and the continuity of life and safety.

Matthews explained the meaning of pollen: ‘Pollen is the emblem of peace, of happiness, of prosperity, and it is supposed to bring these blessings.  When, in the Origin Legend, one of the war gods bids his enemy to put his feet down in pollen he constrains him to peace.’  When in prayer the devotee says, ‘May the trail be in pollen’ he pleads for a happy and peaceful life.”2



The Parts of a Flower

Before we look specifically at pollen it is helpful to recall the parts of the flower:

  • Pistil w/ stigma, style, stylar canal, ovary, locule, funicle, embryo sac, and nucelius (Female)
  • Stamens w/ anther and filament (Male)
  • Petals (Corolla)
  • Calyx (Sepals)
  • Receptacle


Inside the anthers are the pollen grains.  “Most anthers have two sacs (thecae) separated by a connective tissue.  Each theca is separated into two compartments (locules).

“At maturity the two thecae split open, usually longitudinally, to release the pollen grains from the locules in hundreds and thousands.”3

They can also split horizontally, by pores, or valvate (with little hinged doors).


Pollen is released as individual grains, in tetrads, as polyads (usually grains of 4), or as coherent masses (massulae).

A pollinium is a coherent mass of pollen grains that is the product of only one anther, but is transferred during pollination as a single unit.  This is regularly seen in orchids and some milkweeds.

Orchid Pollen



Parts of a Pollen Grain

Pollen grains are functional and efficient.  They are composed of the following parts:

  • Pollen Wall
  • Exine – outer wall composed of sporopollenin – one of the toughest plant substances known
    • “Given the right conditions for burial and preservation this tough outer casing can resist decay and remain structurally unaltered in a ‘mummified state’ for millions of years.”4
  • Apetures – in the exine for the exit of the germinating pollen tube which carries the reproductive cells from the pollen grain to the ovule.
  • Pollenkitt – a sticky coating of oily lipids on the exine in some species
  • Intine – inner wall
  • Cytoplasm – fills the interior of the mature pollen grain
    • Vegetative & Generative Cells w/ organelles – suspended in the cytoplasm


“When a pollen grain lands on the surface of a stigma a recognition chemical, contained on or within the surface of the pollen grain, will trigger a negative signal or a positive signal.  A positive signal indicates that the pollen grain seems to be ‘compatible’ i.e. from the same plant.

Following successful acceptance by the stigma, usually in competition with hundreds, even thousands, of other pollen grains, each pollen grain instantly becomes involved in a fierce race to be first to deliver its sperm cells to an ovule – but first the sperm cells must get through one of the apertures in the pollen wall.  This happens as follows:

On contact the pollen grain absorbs moisture from the receptive surface of the stigma.  The intine (inner wall) begins to expand below an aperture where it is thickest.  The aperture membrane splits open and the intine forces its way through this opening.  The extruding intine – the pollen tube – surrounds the cellular material from the pollen grain containing the vegetative and sperm cells.

Pollen tube cells are the fastest growing of all plant cells, because they are competing against each other to be first to reach an ovule.

On arrival in the ovary the vegetative nucleus disintegrates, and the sperm cells are stripped of their cytoplasm, before continuing into the embryo sac of the ovule.  Here one fuses with the ovum (egg nucleus) to form the embryo, and the other fuses with the polar nuclei…from which the endosperm will develop.

The beautiful outer casing of the pollen grain lies crumpled and discarded on the stigma surface, its function fully discharged.”5



Geometric Pollen Structures

The Platonic solids, especially the icosahedron and dodecahedron can be seen in the pollen grains of many species of plants:

Stellaria holostea – Greater Stitchwort pollen – dodecahedral


Acacia pollen (Rice’s Wattle – Fabaceae Mimusoideae)


Drimys winteri pollen (Winter’s Bark)


Ambrosia spp. (Ragweed) Pollen


Helianthos (Sunflower) pollen grains


Tihonia rotundifolia (Mexican sunflower) pollen


Hibiscus pollen grains

Credit: Nick Fedele


Ipomoea purpurea (morning glory) pollen


Aquifoliaceae (Holly), Ilex aquifolium


Lily (Liliaceae) pollen


Quercus coccifera (Kermes oak) pollen

Credit: Zeiss Microscopy


Ricinus communis sanguineus (castor bean or castor oil plant) pollen


Common mallow pollen

Credit: Nick Wood


Origanum vulgare (oregano) pollen


Sage Pollen


Olea Europea (olive) pollen

Credit: Zeiss Microscopy


Halothamnus (saltbush) pollen – icosa-dodecahedral


Cucumber pollen – triangular/deltoid shaped pollen grains


Asteraceae (daisy spp.) – polyhedral

Credit: Nick Wood


Brassica napus (rapeseed) – hexagonal sculpturing of pollen wall


Oregon-grape holly pollen – Note the pentagon in the center of the right grain.

Credit: Nick Wood


Witch Hazel (Hamamelidaceae)


Hibiscus spinifex – Ginger Bush (Malvaceae)


Passion flower (Passiflora caerulea)


Mpumalanga Sagebrush (Hemizygia transvaalensis)


Forked Catchfly (Silene dichotoma)


Malabar spinach (Basella alba) & Malabar nightshade (Basella rubra)


Walnut (Juglans regia)


Iris decora – a ‘Juno group’ Iris


Goat’s beard, Jack-go-to-bed-at-noon (Tragopogon pratensis Minor)


“Why is it necessary for plants to have such an elaborate structure as the pollen wall to contain their sperm cells when the sperm cells of animals are naked and they procreate successfully?  The reason is simple:  animal sperm cells pass from male to female in a moist environment.”6

Plant sperm cells must be in an air-tight container so they will not dry out.

The book Pollen: The Hidden Sexuality of Flowers is highly recommended.  Credit: Rob Kesseler


“Why such an array of fantastic modifications to the original simple mono- and tri-aperturate ‘prototypes’ should have developed is not easy to explain other than as evolutionary adaptations or developmental modifications.”7

Perhaps nature is an artist, as well as a scientist.  Efficient function can take many forms.  Perhaps nature likes to see how many different forms it can take and still get the job done, so to speak.



Pollen – by Moya Cannon8


And this dust survives

Through the death of ages.

It sleeps in deep layers of mud

Black, red and umber;

It sleeps under the wet pelt of a November hill

Where long grass is the colour of fox;

It sleeps deep under lakes;

Twelve metres down it survives,

Dust of arctic meadows,

Old and tough

As love.


  1. Kesseler, Rob & Harley, Madeline, Pollen: The Hidden Sexuality of Flowers, Earth Aware Traditions, 2014
  2. Reichard, Gladys A. Navajo Religion, Vol. I, 1950,
  3. Kesseler, Rob & Harley, Madeline, Pollen: The Hidden Sexuality of Flowers, Earth Aware Traditions, 2014
  4. ibid.
  5. ibid.
  6. ibid.
  7. ibid.
  8. Cannon, Moya, The Wake Forest Series of Irish Poetry, Volume II, 2010


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