Saturday, August 6, 2011

Structural genetics: the perpetuation of evolutionary models successfully

When nature is able to generate a successful structure in a living being, perpetuates the genes that encode the new things emerged by evolution from primordial ancestor. Never mind the millions of years separating them. The basic structure, the intimate setting of its anatomy is always essentially the same and of course genes too.

One of the basic structures are the most striking inflorescences of conifers and palm trees that bear a remarkable resemblance to the fertile fronds of the Osmundaceae family ferns. Pollen from these inflorescences are dispersed by anemocoria through wind, just like the spores of the fern sporangia.

 Fertile fronds of the fern Osmunda regalis end of which develops a branching structure of sporangia naked without indusium. When the spores mature, the wind scattered as far away from its mother to conquer new territory.

Detail of the reproductive structure of Osmunda regalis.

Pinus halepensis male inflorescence loaded with pollen is dispersed by the wind. Each set of flowers is very similar structural groups of sporangia of the fern Osmunda regalis.

Male inflorescence of Pinus canariensis. These flowers without petals and no nectar have no attraction for pollinating insects. Pollen is dispersed by anemocoria through wind.

 Pinus canariensis branch with male inflorescences.

Male inflorescence of the palm Syagrus romanzoffiana called Coco feathery Brazil, formed by groups branched pollen-laden flowers as in all these plants are dispersed by wind. Its basic structure is identical to the fertile fronds of Osmunda regalis.

If we extended this image with a double click we will be able to see the masculine inflorescences of this palm of the fortune, Trachycarpus fortunei, original of China. As all the masculine inflorescences of the Arecaceae keep a great structural similarity with the groups from esporangia of the fertile fronds of the Osmundaceae.

If we delve into the intimacy of these structures and focus on each of the subgroups of sporangia and male flowers, we will find even more similarities. A striking example is the strobili of the ferns of the families of the Ophioglossaceae and Equisetaceae and inflorescences of the Cupressaceae, Cycadaceae and Pinaceae.

 Fertile fronds of the fern Equisetum telmateia with strobili in its extremes.

Each strobilus consists of a conical structure of sporangiophores with sacks of sporangia on the inside.

 Equisetum telmateia strobilus with hexagonal sporangiophores in the form of honeycomb that are spreading to allow the dispersal of spores.

Equisetum telmateia spores bags breaking off and start their dispersal by wind.

Giant Cycas revoluta male inflorescence with a conical structure identical to the strobili of the Equisetaceae.

Close-up image of the previous inflorescence with separate scales for the wind to disperse pollen from the flowers without petals hidden in the back of the inflorescence.

Masculine inflorescences of Zamia furfuracea, an extraordinarily primitive Mexican plant. Its inflorescences are identical to the strobili of the Equisetum.

  In this image we can see the interior of a masculine inflorescence of  Zamia furfuracea with the small already empty coats of pollen after its dispersion by the wind. Its structure surprises by its great similarity with the coats of esporangia of a Equisetum. A few million years of evolution allowed to give the jump of spores to pollen, or rather, of masculine microspores to pollen, since the feminine megaspores were transformed into seeds.

Looking at each of the small subgroups of male flowers of the inflorescence of Pinus canariensis, we note its resemblance to the strobili of the Equisetaceae and inflorescences of the Cycadaceae and Zamiaceae.

These beautiful male inflorescences of Abies pinsapo also have the same structure as the strobili of the Equisetaceae, Zamiaceae and Cycadaceae.

A simplified structure very similar to the above is that of the tiny strobilus of fern Ophioglossum lusitanicum formed by two rows of sporangia.

Another example are these tiny simplified inflorescences of Tetraclinis articulata conifer, endemic to Murcia. Each ones have a basic structure identical to the previous examples.

Also, the male catkins of hazel follow the same pattern that a structural and functional fertile frond Osmunda regalis.

Macroscopic image of a hazel catkins with trefoil detail cottony scales which separate at maturity and thus allow the pollen grains contained in the 8 stamens are hidden on the inside could be dispersed by wind.

If we look at the female inflorescences of these plants will see their basic structure also bears a remarkable resemblance to the strobili of the ferns Ophioglossum and Equisetum. Nature is very conservative and has a strong tendency for the economy. When, after many experiments to get a successful structure, stop wasting time and energy in finding new adaptations and merely repeating the same structure in all living descendants of the primeval. Only in some cases partially changed some details for better reproductive efficiency and/or adaptive.

Tiny female inflorescence of Pinus halepensis, almost equal to the strobilus of the ferns of the family Equisetaceae.

Female inflorescence of Pinus pinea.

Strobilus of Equisetum ramosissimum.

Detail of sporangiophores in the form of honeycomb cells.

 Female inflorescence of Encephalartos lehmannii of South Africa the family Zamiaceae, an antediluvian plant midway between a fern and a conifer. In fact it has found a possible ancestor fossil unfortunately extinct. Fern was a very evolved which was capable of producing female megaspores were not dispersed by wind but remained in the sporangium, it germinated and gave rise to a female gametophyte with a oosphere, which was fertilized by a antherozoids from a male gametophyte. After fertilization, an embryo is formed, a paralyzing sporophyte growth and entered diapause or resting. Had just been born the first seed. When dropped in a suitable medium, restarted the growth of the embryo and gave rise to a new plant, the first capable of reproducing by seed.

Female inflorescence of Macrozamia communis, Burrawang call, also a very primitive plant native to New South Wales in Australia.

 The structure of this feminine inflorescence of Macrozamia communis is looked extraordinarily like a conifer cone, a tropical pineapple, an strobilus of Equisetum, etc. I recommend to extend the photo with a double click.

Bromeliaceae also have a strobilus-like inflorescences of Equisetaceae. Here is the inflorescence of pineapple, Ananas comosus, a very primitive plant also holds a remarkable resemblance in its inflorescence with Cycadaceae and Zamiaceae.

Pineapple of Pinus pinea, whose grudges are abren when maturing and allow the dispersion of the pinions. If they have luck and they fall in a very illuminated place far from the shade of its mother, they germinate and little by little it is formed a small copse of brother pines. If we paid attention to the structure of this pineapple and we compared it with strobilus of Equisetum, the grudges would be the hexagonal sporangiophores slightly modified and the great pinions would be the equivalent to the coats of spores. Since or we have seen previously in the explanation of the birth of the first seed proper in the extinguished fern, each of these great pinions would be in fact the oosphere of a feminine gametophyte been born from a megaspore that has been fertilized by a anterozoide or grain of pollen taken by the wind coming from a masculine gametophyte. These fertilized oospheres or pinions with the sporophyte or embryo partially developed in their interior grow of two in two occupying all the space that occupied million ago years the coats of spores of the sporangia of their original ancestor, that had the audacity to give a great jump in the evolution and transformed megaspores into seeds. The Spermatophytas or superior plants that reproduce by seeds were born this way.

A tree whose fruit shaped strobilus clearly speak us of its age or primitivism is the Magnolia grandiflora. The basic structure remains the same with very small variations.

 The scales of the fruit remind us the sporangiophores of a strobilus of Equisetum, the scales of the male flowers of the hazel tree and the Murcian conifer  Tetraclinis articulata, the scales of the pineapple, the female fruit of Macrozamia communis and the male strobilus of Cycas revoluta.

The beautiful red fruits of Magnolia grandiflora would be female oospheres transformed into seeds. The Magnoliaceae are trees with flowers, beautiful flowers by the way, however their fruits have remained unchanged over millions of years. They have not had any need to change the structural model. It has been great,  allowing them to survive innumerable climatic changes.

Many other plants, generally very primitive have inflorescences in strobilus more or less modified. This is the case of the Araceae, whose reproductive system has ceased to depend on wind for pollen dispersal and has evolved to adapt to the rotten flies that are their pollinators. One of the most famous is the Araceae Amorphophallus titanum, the world's largest flower.

 Arum italicum inflorescence with fragrant spadix-like strobilus that emits an unpleasant smell of rotting meat and attracts meat flies.

Intimate anatomy of the inflorescence of Arum italicum. When a meat fly, attracted by her favorite perfume, lands on the inner surface of the spathe, the hair falls over and slides down toward the bottom of the inflorescence, where the female flowers. Once inside it realizes the deception and want to leave, but the down hairs prevent it. Other flies, some with their bodies covered with pollen from another Arum, fall into the same trap and desperate to go out again and again over the female flowers and pollinate them. When Arum find that its female flowers have been fertilized, mature male flowers which are covered with pollen. Dehydrated while leaving the hair down to a barrier and flies can go, but they goes over the male flowers and take with them the Arum pollen. Once outside, desperate with hunger are lured by the inflorescences of other Arum and starts other time the process of pollination.

As much the masculine flowers as the feminine ones have a great similarity with the sporangiophores of strobilus of Equisetum telmateia.

Other Araceae, the Monstera deliciosa, also has its inflorescence as strobilus.

Its fruits have the form and the typical structure of a strobilus.

So great it is the similarity of the inflorescence of Monstera deliciosa with a strobilus that even repeats faithfully the hexagonal structure of the sporangiophores of Equisetum telmateia. In the case of the Monstera deliciosa the masculine flowers are hidden between the hexagonal feminine flowers. It is seen leave pollen between the hexagons. This one is perhaps the most demonstrative example of the repetition of a successful evolutionary model.

Combined image with the comparison of the hexagons of Equisetum telmateia and Monstera deliciosa.

And for to finish these beautiful purple inflorescences of Arum pictum, Tyrrhenian endemism growing in Corsica, Sardinia, Mallorca and Menorca. Its spadix nearly black also has the structure in strobilus.


  1. Hello Juan,
    I have been following your blog for sometime and i find it very interesting. Congratulations for the good work.
    I also would like to ask you for you permission to use 2 photos (details of intimacy of Arum italicum) in my blog Plantas e Flores do Areal. If you agree I will mention the source in my post. Do you give me your permission? Muchas gracias

  2. Hola Fernanda:

    De acuerdo, puedes usar las dos fotos haciendo constar que son propiedad del Jardín Mundani con un enlace hacia este post de mi Blog.

    Un saludo

    1. Hola Juan,
      Muchas gracias por respuesta tan pronta y por tu permission. De acuerdo, me pongo un enlace a tu Blog y dare una indicación de la propiedad de las fotos.
      Gracias y saludos

  3. Fascinating, as are all your other enjoyable and very enlightening posts!! Thank you!