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Catalpa speciosa/bignonioides/ovata

Inviato: 27 mag 2013, 22:55
da Enrico Banfi
Per adesso lasciamo la determinazione in forma indicativa, perché purtroppo il carattere dell'odore della foglia stropicciata non sembra funzionare come si pensa. La distinzione tra le due specie è davvero molto debole e se non crescessero una al Nord (speciosa) e una al Sud (bignonioides) degli USA, sarebbero già state considerate appartenenti a una sola specie. In mancanza di revisioni recenti (sono tutte vecchie) e di impostazione moderna, riporto qui sotto lo stralcio di una descrizione delle due specie da me prelevato (copia/incolla) un po' di tempo fa in una discussione di un forum americano, di cui purtroppo non ho preso gli estremi. Serve solo per capire che cosa pensano i legittimi "coinquilini" delle catalpe rispetto alle differenze tra le due specie.


Catalpa speciosa Warder ex Engelm.

midwestern United States.

It is a medium-sized, deciduous tree growing to 15-30 meters tall and 12 meters wide. It has a trunk up to 1 m diameter, with brown to gray bark maturing into hard plates or ridges. The leaves are deciduous, opposite (or whorled), large, heart shaped, 20-30 cm long and 15-20 cm broad, pointed at the tip and softly hairy beneath. The flowers are 3-6 cm across, trumpet shaped, white with yellow stripes and purple spots inside; they grow in panicles of 10-30. The catalpa tree is the last tree to grow leaves in the spring. The leaves generally do not color in autumn before falling, instead, they either fall abruptly after the first hard freeze, or turn a slightly yellow-brown before dropping off. The winter twigs of northern catalpa are like those of few other trees, having sunken leaf scars that resemble suction cups. Their whorled arrangement (three scars per node) around the twigs is another diagnostic.
The fruit is a long, thin legume-like pod, 20-40 cm long and 10-12 mm diameter; it often stays attached to tree during winter (and can be mistaken for brown icicles). The pod contains numerous flat, light brown seeds with two papery wings.
It is closely related to southern catalpa, and can be distinguished by the flowering panicles, which bear a smaller number of larger flowers, and the slightly broader seed pods.

Catalpa bignonioides Walter

southern (compactly southeastern) United States

It is a medium-sized deciduous tree growing to 15-18 meters tall, with a trunk up to 1 m diameter with brown to gray bark, maturing into hard plates or ridges. The short thick trunk supports long and straggling branches which form a broad and irregular head. The roots are fibrous and branches are brittle. Its juices are watery and bitter.[2]
The leaves are large and heart shaped, being 20-30 cm long and 15-20 cm broad. The bright green leaves appear late and as they are full grown before the flower clusters open, add much to the beauty of the blossoming tree. They secrete nectar, a most unusual characteristic for leaves, by means of groups of tiny glands in the axils of the primary veins.[2]
The flowers are 2.5-4 cm across, trumpet shaped, white with yellow spots inside; they grow inpanicles of 20-40. In the northern states of the USA, it is a late bloomer, putting forth great panicles of white flowers in June or early in July when the flowers of other trees have mostly faded. These cover the tree so thickly as almost to conceal the full grown leaves. The general effect of the flower cluster is a pure white, but the individual corolla is spotted with purple and gold, and some of these spots are arranged in lines along a ridge, so as to lead directly to the honey sweets within. A single flower when fully expanded is two inches long and an inch and a half wide. It is two-lipped and the lips are lobed, two lobes above and three below, as is not uncommon with such corollas. The flower is perfect, possessing both stamens and pistils; nevertheless, the law of elimination is at work and of the five stamens that we should expect to find, three have aborted, ceased to bear anthers and have become filaments simply. Then, too, the flowers refuse to be self-fertilized. Each flower has its own stamens and its own stigma but the lobes of the stigma remain closed until after the anthers have opened and discharged their pollen; after they have withered and become effective then the stigma opens and invites the wandering bee. The entire Pink family (Bignoniaceae) behave in this way.
The fruit is a long, thin bean like pod 20-40 cm long and 8-10 mm diameter; it often stays attached to tree during winter. The pod contains numerous flat light brown seeds with two papery wings.
It is closely related to the Northern Catalpa (C. speciosa), and can be distinguished by the flowering panicles, which bear a larger number of smaller flowers, and the slightly slenderer seed pods.

Re: Catalpa speciosa (Warder) Engelm.?

Inviato: 27 mag 2013, 23:26
da Enrico Banfi
Dimenticavo di aggiungere che si coltiva pure (e al Nord tende a naturalizzare) Catalpa ovata G. Don della Cina himalayana e che, in mancanza di fiori e frutti, potrebbe benissimo corrispondere anche lei alla pianta di Deadly. Però, a differenza delle due americane, ha le foglie scabre, cioè ruvide sopra e sotto. Per poter eventualmente escludere la catalpa cinese, Deadly, prova a passare le dita sulla superficie delle foglie per verificare se sono ruvide oppure no; se fossero ruvide dobbiamo pensare che si tratti di C. ovata

Enrico :bye:

Re: Catalpa speciosa (Warder) Engelm.?

Inviato: 28 mag 2013, 21:54
da Enrico Banfi
YES! Le altre due hanno superficie fogliare liscia. Poi, eventualmente, se ti capiterà di rivedere la pianta in fiore, guarda subito il colore dei fiori: se sono bianchi di fondo con "disegni" rossi allora è una delle due fatidiche specie americane, se invece il colore di fondo è giallo pallido o giallo crema allora si tratta di C. ovata. Buon divertimento!