Acanthaceae

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Acanthus Family

Ruellia metallica Leonard, an herb in the Acanthaceae. Note the subentire margins of the leaves, the stems swollen above the nodes, and the papery inflorescence bracts. Una hierba. Note las márgenes dentadas de las hojas, el tallo engrosado arriba de los nudos, y las brácteas llamativas de la inflorescencia.


Description: A large and important family of herbs, shrubs, and soft-wooded trees, with a few lianas (Mendoncia). Acanthaceae have opposite leaves that are almost always toothed and usually anisophyllous (i.e., the two leaves in a pair are slightly different sizes). They lack stipules, but they have an interpetiolar ridge (a ridge of tissue running between the leaf bases) that can superficially resemble a stipule scar. The stems of Acanthaceae tend to be succulent and slightly swollen above the nodes, and may be ridged. Acanthaceae flowers are bilaterally symmetrical, with a fused 5-lobed corolla and four (sometimes two) stamens. The anthers join together in the center of the flower beneath the style. The flowers are often subtended by bracts, which may be the showier part of the inflorescence.

Economic uses: Many Acanthaceae are grown as ornamentals. Thunbergia is particularly popular here.


Descripción: Una familia importante y rica en especies de hierbas, arbustos, árboles con madera suave, y algunos bejucos (Mendoncia). Las Acanthaceas tienen hojas opuestas, casi siempre dentadas, y usualmente anisófilas (es decir, las dos hojas de un nudo son de tamaños diferentes). Carecen de estípulas, pero tienen una protuberancia interpeciolar que une las bases de las hojas, superficialmente similar a la cicatriz de una estípula interpeciolar. Los tallos de las Acanthaceas usualmente son suculentos y un poco engrosados arriba de los nudos, y en algunas ocasiones son alados. Las flores de las Acanthaceas son bilateralmente simétricas, con una corola tubular con cinco lóbulos, y cuatro (a veces dos) estambres. Las anteras se unen en el centro de la flor, bajo el estilo. Usualmente hay brácteas debajo de las flores, que pueden ser la parte más llamativa de la inflorescencia.

Usos económicos: Muchas especies de Acanthaceas son ornamentales. Thunbergia es muy popular en esta zona.


Genera/species at La Selva: 14/33: Herbs/ hierbas: Aphelandra (4), Barleria (1), Blechum (2), Dicliptera (1), Herpetacanthus (1), Hygrophila (1), Justicia (6), Louteridium (1), Odontonema (2), Razisea (2), Ruellia (4) Lianas/ bejucos: Mendoncia (3), Thunbergia (4) Trees/ árboles: Bravaisia (1).


FIELD MARKS – opposite, simple leaves, within a pair of leaves one is often larger (anisophylly), swollen nodes, often with horizontal scars at nodes between the petioles.


Opposite leaves, slightly swollen nodes, and a horizontal scar between petioles are diagnostic of Acanthaceae.
Opposite leaves, slightly swollen nodes, and a horizontal scar between petioles are diagnostic of Acanthaceae.
Opposite leaves with a scar or ridge between the petioles and a slight swelling at the nodes identifies Odontonema cuspidatum as a member of the Acanthaceae.
Odontonema cuspidatum inflorescence bearing red flowers that are pollinated by hummingbirds.


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