Paleo-autochtonous species (2): Nyssa

Leaves of Nyssa sylvatica in autumn.

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Little known and still little used in our country (Spain), the tupelos (Nyssa), are deciduous trees that are highly valued in other countries for their magnificent autumnal colors. There are currently 8 species recognized in this genus, all with fairly high water requirements. The most commonly cultivated and with the largest distribution area (N. sylvatica and N. sinensis) are typical of wet and riverine forests. Others, such as N. aquatica, N. biflora or N. ogeche (all north american), are adapted to live in marshy areas and have a broad base very typical of the trees that grow in this type of environment, such as the bald cypress (Taxodium distichum) where they live together in many places. In our country (Spain) it is still rare to see them, although it is already possible to obtain N. sylvatica in some nurseries.



The tupelos flowers are not very flashy. These belong to N. sylvatica. / Picture: Using georgia native Plants

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The genus Nyssa is another taxon with a disjoint distribution area at the continental level, with 5 species in eastern North America and 3 in East Asia. The genus, as might be expected, was also present on the European continent before the ice age, where different fossil species more or less related to the present species were described. As can be seen on the map, the most recent citations come from the Mediterranean basin (Middle Pleistocene) and the Caspian Sea region, where they seem to have survived until the last interglacial period (Eemian) in the river Emba delta. It really lacked them very little to survive on our continent.

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Together with other small genera (Camptotheca, Davidia, Diplopanax, Mastixia), this genus constitutes the small family of Nyssaceae, related to the family of Cornaceae, in which they were still included in the APG III classification. Nisaceae, like most Cornales, still have primitive features such as free petals and arboreal size, which can also be observed in the neighboring order of the Ericales, for example.

	Nyssa	Family: Nyssaceae	Order: Cornales
	Trees dioecious or functionally dioecious (with anthers of bisexual flowers that do not dehisce); bark gray brown, rough, ridged; twigs with transverse diaphragms; winter buds scaly. Leaves alternate, simple, often crowded near ends of branches, estipulate; petiole terete or winged; blade usually elliptic to oblanceolate or obovate, rarely ovate, base cuneate to rounded. Flowers unisexual, usually in heads or short racemes, in axil of a bract with 2 bracteoles; sepals forming a low rim; petals greenish to greenish white. Male flowers 5-merous, pedicelate or not. Stamens 10, arranged in two alternate whorls; filaments linear; anthers 2-celled, dorsifixed, with lateral lengthwise slits; disk pulvinate. Female flowers (4 or)5-merous, not pedicelate; staminodes usually present. Ovary inferior, 1(or 2)-loculed, 1-ovuled; style subulate or conic, bifid, with stigmatic tissue at inside of stylar arms. Fruit drupaceous, ± laterally flattened, with persistent calyx and disk, usually blue-black (sometimes reddish purple in N. aquatica; yellow, orange, or red in N. ogeche); mesocarp juicy, acidic. n = 22. Description: eFloras

The only species that is occasionally cultivated in the Iberian Peninsula is Nyssa sylvatica which, however, is sensitive to frost when young and difficult to transplant. This makes it relatively rare and one has to go to arboretums or botanical gardens to observe it.



Nyssa sylvatica fruits / Picture: Great Plains Nursery

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Author: Adrián Rodríguez
Translation: João Ferro

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Paleo-autochtonous species (1): Carpinus

Leaves and inflorescences of European or common hornbeam (Carpinus betulus).

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If one species deserves more than any other, the name of "paleo autochthonous", whatever the meaning one may wish to give to this neologism, this is without question the European or common hornbeam (Carpinus betulus). This species is still present reliquely in the valley of Bidasoa (Spain), but in the recent past has had a much more extensive distribution area in the Iberian Peninsula. And you do not have to go back too much in time or in the past to find marks of it's presence. In much of northern peninsula and the Atlantic strip, its presence was confirmed during the climatic optimum of the Holocene, when it reached the Iberian Central System [1]. Their current locations are therefore, the last testimonies of a much wider presence. It would then be necessary to ask why it disappeared from many of the localities that it reached at that time. The most probable explanations of such regression are the progressive increase of the seasonality after this climatic optimum reached between 9000 and 5000 years before the present and the beginning of the agricultural exploitation of the lands that were more favorable to this species.




The common hornbeam is a very demanding species, with water and soil requirements that are not often found on the Peninsula today. It is not a species that tolerates drought and develops preferentially in rich and deep soils that are usually what we normally find in lowland areas. It is, on the other hand, a species that bears the heat very well, being perfectly capable, if irrigated, of enduring the implacable summers of the center of the Peninsula. Some specimens planted in my neighborhood (Madrid) already measure about 4 to 6 meters, bloom and bear fruit each year, bearing without much trouble the 40 degrees that are reached in July and August. At most, some of the leaves dry up, but this does not endanger the survival of these trees.



Maps of the current distribution of European hornbeam (C. betulus) and Oriental hornbeam (C. orientalis) [2].

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In times prior to the last ice age, the common hornbeam was present in much of the Peninsula, it must also be highlighted the presence at the end of the beginning of the Pliocene and during the Pleistocene of Eastern hornbeam, today present only in the East of the continent and the Mediterranean basin, what should also be noted. The Eastern hornbeam is not a vicarious species. It is a hornbeam better adapted to the drought than C. betulus, which makes it, in Eastern Europe, a typical element of the sub-Mediterranean vegetation, living there with species such as the downy oak (Quercus pubescens), the Turkey oak (Quercus cerris) or the European hop-hornbeam (Ostrya carpinifolia). That is because of its ecology, is quite different from the common hornbeam, which is a species of sub-Atlantic and central European environment.

	Carpinus	Familia: Betulaceae	Orden: Fagales
	Trees or shrubs. Fusiform and sharp buttons. Leaves oval or oval-elliptic, acute, doubly serrated, with 9 or more pairs of very marked and regular secondary nerves. Male catkins are solitary and sessile; bare flowers, solitary in the armpit of each bract, without bracing; Stamens 6-20, pubescent, with bifid filaments, very short. Female terminal limbs, relaxed, pendent at maturity, with leafy bracts; twinned flowers, with perianth; seminal rudiments 1 (2); style divided into 2 filiform, green branches. Achenes arranged in hanging ears, small and compressed, surrounded by a large folium, trilobed or serrated, with sharp venation, originated by addition of the single bract.

Also noteworthy here is the unexpected presence of the hornbeam in the Canary Islands until the end of the Holocene. [3] More surprising perhaps, because of the distance than because of the climatic conditions. This presence is not so surprising, however, knowing that it was also present in the mountainous masses of the Sahara in times much more humid than today.

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Fruit of Carpinus betulus (top) compared to Carpinus orientalis (bottom).

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The common hornbeam is a species commonly cultivated in our country (Spain), where it surprises in many places by its capacity to withstand the high summer temperatures. As mentioned earlier, lack of water seems to be the true limiting factor for this species. On the other hand, surprisingly, the cultivation of Eastern hornbeam did not aroused much interest in our country (Spain). This being a much less demanding tree, it is curious that it has not been tried at least in our parks and gardens. Being a tree of relatively small dimensions, which often is not even more then a bush, it can be understood that it did not arouse the interest of the foresters. It would, however, be an element to take into account to increase the biodiversity of our forests in areas of sub-Mediterranean climate, where in addition to the everlasting Quercus, the hardwoods do not abound.

I planted some seeds of Carpinus orientalis a few years ago, with no treatment and none of them germinated. Last year, however, I saw two small little trees appear in my pots that may well correspond to this species or perhaps to the European hop-hornbeam, I can not name them for now. Next year I will have to try again, since this species seems very interesting for the climatic conditions of the Iberian Peninsula.

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Author: Adrián Rodríguez
Translation: João Ferro

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