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Euphorb Family

Hura crepitans L., a tree in the Euphorbiaceae. A fair number of Euphorbs have leaves of this general shape, but there are really no good vegetative characters for the family. Un árbol. Muchas Euphorbiaceas tienen hojas más o menos de este forma, pero en realidad no hay características vegetativas útiles para la identificación de esta familia.

Description: Vegetatively, the Euphorbiaceae are distressingly variable. There is little to unite them on first glance. As Gentry (1993) remarks, Euphorbiaceae and Flacourtiaceae are the “garbage pail” families of tropical botany. If you can’t figure out which family a plant belongs to, chances are it’s one of these. Euphorb leaves are usually alternate, simple to palmately compound, and often with stellate trichomes and/or obvious glands. Many genera have white latex. They all have stipules, some large and some almost indiscernible. The fruits of Euphorbiaceae are generally 3-locular schizocarpic capsules (i.e., three-chambered dry capsules that split open to release the seeds). In growth habit, euphorbs vary from weedy herbs to large emergent trees.

Economic uses: Some large euphorb trees are used for timber. Hevea brasiliensis, the rubber tree, was once a very important cash crop in the Amazon. Manihot esculenta is the source of manioc (yuca), which is a staple throughout the Amazon and much of Central America and the Carribean. On the more prosaic side of things, some euphorbs are common houseplants: Acalypha spp. (“chenille plant”) and Poinsettia.

Descripción: Desafortunadamente, no hay muy buenas características que se puede usar para identificar las Euphorbiaceas estériles. Como dice Gentry (1993), Euphorbiaceas y Flacourtiaceas son las “familias basurero” de la botánica tropical. Si hay una planta desconocida sin características útiles que se puede usar para saber la familia, probablemente es de una de esas familias. Las Euphorbiaceas usualmente tienen hojas alternas, simples a palmaticompuestas, y muchas veces con pelos estrellados y/o glándulas. Muchos géneros tienen savia blanca. Todos tienen estípulas, unas grandes, y unas casi invisibles. Los frutos de las Euphorbiaceas por lo general son esquizocarpas con tres lóculos (es decir, cápsulas secas de tres partes que abren para dejar caer a las semillas). El hábito de las Euphorbiaceas varía desde hierbas hasta árboles enormes.

Usos económicos: Algunas especies de árboles son maderables. La savia de Hevea brasiliensis (caucho o cauchuc) por muchos años fue un producto de exportación de gran importancia en el Amazonas. Manihot esculenta (yuca) es una de las principales cosechas en el Amazonas y en muchas áreas de Centroamérica., Algunas especies (p. ej. Acalypha y Poinsettia) se cultiva como ornamentales.

Genera/species at La Selva: 27/54. Aquatic plants/ plantas acuáticas: Caperonia (1) Herbs/ hierbas: Acalypha (some of the 7 species here/ unas de las 7), Chamaesyce (4), Euphorbia (5), Phyllanthus (5) Shrubs/ arbustos: Acalypha (some of the 7), Croton (6), Jatropha (2), Manihot (2), Ricinus (1) Vines (non-woody)/ bejucos no leñosos: Dalechampia (2), Tragia (1) Lianas/ bejucos leñosos: Omphalea (1), Plukenetia (1) Trees/ árboles: Adelia (1), Alchornea (2), Alchorneopsis (1), Caryodendron (1), Conceveiba (1), Drypetes (1), Hevea (1), Hura (1), Hieronyma (2), Mabea (1), Pera (1), Richeria (1), Sapium (2), Tetrorchidium (2)

FIELD MARKS – Due to the wide variation of traits within this diverse family, field marks are presented for select species. Most exude copious white latex.

Hieronyma alchornioides – canopy emergent tree, light brown trunk with buttresses, simple alternate leaves clustered at branch tips, stipules, fallen yellow and red leaves aid in identification.

Hieronyma alchornieoides is a giant tree that can reach heights of 40 m. Dr. Susan Letcher is standing next to a tree located near the steps leading out of Cantarana Swamp.
Prior to falling from the tree, the leaves of Hieronyma alchornieoides turn colors reminiscent of autumn in New England.
Staring up the trunk of a large Hieronyma alchorneioides. Can you spot senescing red leaves in the canopy?

Hura crepitanscordate leaves, 90° angle between petiole and leaf blade, freely flowing watery exudate (unfortunately you need to stab the trunk to view this), trunk covered in sparsely scattered conical spines with a well-defined base.

Medium-sized tree of Hura crepitans
Medium-sized tree of Hura crepitans
Cordate leaves, note the 90° angle between the petiole and blade
Hura crepitans trunk covered with conical spines.
Hura crepitans trunk covered with conical spines.
Large Hura crepitans located at 625 m on STR.
Closeup of Hura trunk showing bumpy spines.
Red conical male inflorescence and leaf of Hura. Note the cordate leaf base and barely visible pair of glands where the petiole meets the blade.

Sapium– alternate, simple leaves, pair of protuberant nectaries on upper surface of petiole close to blade, free stipules, abundant white latex resembling skim milk, fruit a capsule with 3 carpels and 3 locules.

Sapium showing nectaries and copious exudation.
Close-up of nectaries where petiole meets the leaf blade.

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Next family: Fabaceae > >
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