Cloudbridge Nature Reserve

Trees of Cloudbridge

Ulmus mexicana mature Ulmus mexicana (Tirrá, palo baqueta, Mexican elm)

Description: One of the spectacular forest trees of Cloudbridge, having a clear straight bole, unbuttressed and generally unbranched until near the top, sometimes nearly 35 m tall -- one of the tallest trees of the area. The crown is deep, with very dense foliage; almost no light passes through. Our first observations were made in June and July, and on our next visit in December we were shocked to see our favorite tree denuded, and felt anxious as to its health. A few months later we were back at Cloudbridge, and with relief, saw that once again the tree was in its full leafy glory.

Ecology: The tree is shade tolerant and grows slowly until a break in the forest allows it to reach its full canopy or emergent stature. The leaves are host to a variety of lichens, and the crotches of branches are frequently filled with epiphytes -- including strangler figs, which can often be seen establishing a tangle of roots. One often finds U. mexicana growing near Clethra mexicana and Billia colombiana. They grow in pre-montane and montane humid forests, with an annual rainfall between 2500 and 4000 mm.

Distribution: A common canopy tree in the old forest on the western slopes of the Talamanca range, it is often found on steep slopes alongside rivers and canyons. On Cloudbridge, a tall example with light-colored bark and silvery leaves may be seen opposite our house Casa Amanzimtoti, and others across from Cloudbridge Falls. Many grow on Cloudbridge North. In Costa Rica, at medium altitudes of the Central Pacific region, the Tilaran range, the central volcanic range and the Escazú peaks, as well as the Talamancas. They are found between 600m and 2000m elevation from Mexico to Panama.

How to recognize: Distinctive leaves with much-serrated borders.

Uses: Tirra is not one of the most commonly harvested timber trees of Costa Rica because the trunk is often indented and less useful for lumber. Because of deforestation, the species is getting scarcer but is not yet threatened. Apart from at Cloudbridge, few if any are grown in plantations.

Sources and Links:
INBio description
SysTax

Scientific Information:
Division: Magnoliophyta (Flowering plants)
Class: Magnoliopsida (Dicots)
Order: Rosales
Family: Ulmaceae (Elm family)
Species: Ulmus mexicana (Liebm.) Planch (alt. name Chaetoptelea mexicana)


Photo Identification Guide: Ulmus mexicana (Tirrá, Mexican elm)
Leaves.     Simple leaves, alternate arrangement. Shape is elliptic or ovate.
Edges are serrated. Leaves have petioles. The surface of the leaves are glossy, with the underside dull.

The leaves have prominent midribs and veins in the abaxial surface and have arcuate venation.  The size of the leaves can vary from 3.5 cm to 16 cm in length and 2 cm to 7 cm in width.  The petiole of the leaves can vary in length from 5 to 10 mm.


 
Ulmus mexicana leaves
©Barry Hammel Missouri Botanical Garden
Flowers. Flowers are pale green and lighter in tone than the leaves, and they flourish between December and February. Ulmus mexicana fruit
Fruit and Seeds. Fruits have a green-yellowish tone, are flat, lightly elongated and dry, and are 6 to 8 mm in length.  The fruits are all covered with long and straight hairs.  There is one seed per fruit, which is approximately 2 mm in length and of yellowish and flat configuration. The fruit appears in February and March.

Twigs.
Trunk. The tree trunk is grayish, long and straight and approximately 1 m in diameter for mature trees.  The trunk is characterized by demarcated longitudinal indentations all along its length, which makes it less desirable for the timber industry Ulmus mexicana trunk
Form. A clear straight bole, unbuttressed and generally unbranched until near the top, where the leafy brances spread out into a hemisphere.

Saplings. Seedlings and saplings display a characteristic zig-zag stem with well-formed serrated leaves similar to those of the mature plant.
Ulmus mexicana sapling

Cloudbridge: Bridging a Costa Rican cloud forest
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Copyright ©2004 Ian Giddy. All rights reserved. Last updated 5 February 2004