Sticta canariensis, a bigamous liquen with a green wife and a blue one

 In early May, I was descending the steep path of Taganana Turns in the Parque Rural de Anaga located on the northern tip of the island of Tenerife. I went obsessed looking for Asplenium x tagananaense, a rare hybrid fern between Asplenium hemionitis and Asplenium onopteris that around the world is only found in the Anaga massif. In the shady understory of that earthly paradise covered by the high canopy of laurel trees were hundreds of beautiful ferns, but none was Taganana hybrid. Scanning with the view each and every one of the ferns I noticed a very curly endive kind of a nice bright green color. Clinging to the branches of the bushes, climbed a hill on whose floor was a thick layer of humus. When I had the proper footing and I could free my hands, I took my dear compact camera and I made several photos at the giant lichen, the largest I had seen in my life. A few days later, at home, I got to know his identity: Sticta canariensis. (I recommend you double-click on this and the following pictures to appreciate its size and details.)

A lichen is a symbiotic union between a fungus and an alga. For better understanding, we can say that this union becomes a kind of marriage of convenience in which both spouses make a profit. The fungus or mycobiont may be an ascomycete or a basidiomycete, although in most lichens the fungus is an ascomycete. Some ascomycetes fungi can live as independent beings or associated with algae to form lichen. Other ascomycetes can only live as lichens associated with an alga. The transition from independent fungus to symbiotic fungus is considered an advance in evolution, since the association with an alga is very beneficial for the survival of the fungus.

As for the other component, the alga or ficobiont can be a green alga or a blue alga, also called cyanobacteria. The most significant difference between them is that green alga can only perform photosynthesis like any plant, while the cyanobacteria or blue alga has taken a further step in the evolution and besides photosynthesis it is also able to fix atmospheric nitrogen with which provides a valuable component of the symbiosis. This ability to fix nitrogen from the air is of great importance in the formation of fertile soil in the new land emerged after a volcanic eruption.

Almost the entire structure of a liquen is formed by filaments or hyphae, between which are located the unicellular algae. Their union is so intimate and coordination between the two symbionts is so perfect that are able to grow and live as if they were a individual living. The fungus provides water and minerals from the soil, while green alga contributes carbohydrates of fontosíntesis. In the case of blue algae also provides atmospheric nitrogen.

 Image of part of the lichen Sticta canariensis photo above, which are really three copies growing together.

Each component of the union is reproduced separately. The fungus makes it through spores and the algae by simple cell division. However, to form a lichen both symbionts must be in the right place at the right time. The fungus spore germinates if it falls on a substrate with sufficient moisture, but if in that place there are not adequate algae cells the fungus spore die, except if it is an ascomycete able to live alone without an alga. If, however, if near the spore that is germinating there are some algae cells the fungal filaments surrounding the algal cells and start living together. Birth of a lichen.

The high humidity of the understory, the subdued light and the rich substrate decomposed leaves allow it to grow so lush. Without exaggerating copy of this photo was rounded appearance and size of an endive salad.

The ascomycete lichen Sticta canariensis has taken a step in the evolution and achieved two algae associated with different depending on the degree of cold in the region where it grows. In the northernmost regions tends to be associated with blue algae or cyanobacteria leading to a lichen Sticta dufourii color varies according to humidity, sunlight, substrate type, etc ... that can range from pearly beige, green more or less dark gray, brownish or even to black. In the warmer southern regions tend to associate with a green alga leading lichen Sticta canariensis. Sometimes in the intermediate regions are specimens with parts of Sticta dufourii and parts of Sticta canariensis. Would be more like a hybrid lichen.

 Sticta image with parts with green alga and parts with cyanobacteria. It is owned by photographer Ray Woods. I found this great website dedicated to the world of lichens: Lichen Apprentice Scheme Wales

Both species or symbiotic associations are distributed through western Europe and Macaronesia. In Norway and the British Isles dominated the partnership with the blue alga, Sticta dufourii, while in Macaronesia dominated the association with green algae, Sticta canariensis.

 A close-up image allows us to appreciate the apothecia or ascomycete fruiting bodies, where they form spores for reproduction. The algae do not need reproductive organs, because as we have seen is reproduced by simple cell division. Often several cells of the algae stick to the spores of the fungus, so they are easier to disperse much reproduction of the lichen.

Details of the apothecia of the ascomycete red cup shape. All the lichen was soaked in moisture and shines in the darkness of the undergrowth.

White, Black, Yellow: the Sapotes of Mexico

These three subtropical fruits are delicious, sweet, juicy, rare, genuinely Mexican and very little known, three fruits that in time will surely come to be marketed worldwide to become ever faster communications, as one of the limitations for transport is the lack of consistency of ripe fruit. Belong to three different botanical families. The black sapote, Diospyros digyna, belongs to the Ebenaceae family. The Yellow Sapote, Pouteria campechiana is a Sapotaceae. And the White Zapote, Casimiroa edulis, is part of the Rutaceae family.

BLACK SAPOTE

The fruits of black sapote have the typical form and structure of Ebenaceae. At a distance could be confused with the Asian persimmon fruits. The surprise comes from the middle to one of its fruits. The pulp in the optimal stage of maturity is nearly black, shining like jet and creamy. Remember the chocolate mousse.

 Its maturation is very fast as a few hours hard and white pulp of immature fruit softens and darkens. His little consistency is precisely one of the obstacles to their market outside of Mexico. Come to recognize the right time to harvest the fruits ripen on the very day they arrive at the consumer market is one of the challenges to overcome.

In this image of three ripe fruit cut in half in various stages of maturation can be seen as the flesh darkens, the most mature on the right.

 

Enlarging the picture with a double click is better appreciated the creamy texture of the flesh of a shiny jet black color very similar to chocolate mousse. Its flavor is very sweet and reminiscent of burnt sugar fund an egg custard with a touch of honey. We can eat a teaspoon. In the center is three to five seeds. When a tree is dioecious there are male and female feet. As with the persimmons grown trees which are all female, without pollinating the fruits of black sapote mature parthenocarpicaly, presenting in its interior several empty seeds aborted.

The fruits that have been pollinated produce bright brown seeds should be sown immediately because they quickly lose their ability to germinate.

Planted about 20 to 25 ° C germinate within a few days.

Some 14 months later the black sapote previous photo measures approximately 70 cms. The Mediterranean climate without frost is very suitable for cultivation. Can thrive without problems in all areas where citrus and persimmons.

YELLOW SAPOTE

The yellow sapote lives up to its name. For me it is one of the most delicious fruits of Mexico. No need to peel. His skin is very thin and can eat by biting. The center has several elongated seeds dark brown, which quickly lose their ability to germinate, so it should be sown immediately. Its scientific name Pouteria campechiana refers to the Campeche region of Mexico where the fruit originates.

Young yellow sapote of three years old grown on a citrus orchard in Majorca. Tube is drip irrigation. To be able to withstand the hot and dry summer of Mallorca needs irrigation weekly. It also appreciates the contribution of well rotted manure of horse, cow or sheep.

The leaves are light green lanceolate with the distal part wider than the proximal. Yellow sapote is more chilly than black Zapote. If the winter temperature drops to -1 or -2 degrees C, the leaves will burn slightly more exposed. Then at the end of spring regrowth without problems.


WHITE SAPOTE

The white sapote is perhaps one of the most cultivated sapotes outside Mexico. It is not difficult to find for sale in Spanish nurseries, especially in Andalusia, across the Levant region and the Balearic Islands. A Santander´s farmer told me that in Cantabria coast grows well and gives high yields. Is perhaps the least chilly of three Mexican sapotes. His strategy to withstand winter frosts is to behave as deciduous. Thus in the colder months it loses its leaves and wait until temperatures rise in spring. On the coast of Mallorca, if no frost, white sapote behaves like evergreen and keeps its leaves in winter.

White sapote fine specimen 12 years old and about 5 feet grown in a citrus orchard in Majorca. Each year produces a large crop of fruit that will mature over several months. It is a seedless variety.

If winter is mild with temperatures above 5 º C in late January emerges forcefully with beautiful leaves of a deep red color.

 A month later, in February, blooms profusely. The flowers are small and grouped in clusters.

Detail of a flower of white sapote the typical structure of the Rutaceae, much like the flowers of citrus and rue plant.

White sapote trunk bark covered with typical white spots. The specimen has been grafted. It follows by the narrowing in the upper trunk that corresponds to the point of the graft.

Typical white sapote bark of a gray-green cover of white spots.

White sapote ripe fruit that crack when they reach full maturity. To find out if they are mature should be tightened with fingers, because its green color remains unchanged. One of the problems of these fruits are falling from the tree as they mature. It is best to collect them when the pulp is still hard. They tend to mature a few days.

The pulp has a delicious bright white. It is very juicy and overly sweet. The fruit is a seedless cultivar. We will see the aborted seeds in the fruit of the top of the photo. Viable seeds of wild trees are large and elongated. They are much more perishable than those of yellow and black sapote. If we are not allowed to dry after removing them from the fruits and planted immediately to a temperature above 20 º C in less than a week germinate. It is a very fast growing tree.