New Mexico Tree Identification Flashcards

An arborist in the foothills of the Sandia Mountains encounters a small, bushy tree with needles in fascicles of two. The needles are short (1-2 inches), fairly stiff, and yellow-green. The cones are small, reddish-brown, and have thick scales without prickles. This tree is the state tree of New Mexico. Which species has been identified?

Answer: Piñon Pine (Pinus edulis)

The key identifying features are the needles in pairs (two per fascicle), short cone size, and its status as the state tree of New Mexico. Pinus edulis, or Piñon Pine, fits all these characteristics and is common in the pinyon-juniper woodlands of the region.

While assessing a deciduous tree in a client's Albuquerque yard, you note the leaves are alternate, simple, and have 5-9 deep, rounded lobes. The tree has a shrub-like, thicket-forming growth habit, and the client mentions it produces acorns. What is the most likely identification?

Answer: Gambel Oak (Quercus gambelii)

The presence of acorns clearly indicates an oak (Quercus). The description of leaves with deep, rounded lobes and a tendency to form thickets is characteristic of Quercus gambelii, the Gambel Oak, which is widespread in New Mexico's foothills and mountains.

Which of the following characteristics is most useful for distinguishing Juniperus monosperma (One-seed Juniper) from other juniper species in New Mexico?

Answer: Berry-like cones containing a single seed

While all junipers have scale-like leaves, shredding bark, and aromatic foliage, the key diagnostic feature for Juniperus monosperma is in its name, 'monosperma', which means one-seeded. Its berry-like cones typically contain only a single seed, which distinguishes it from other junipers that may have multiple seeds.

A large, deciduous tree growing in the Rio Grande bosque has a broad, open crown, thick, deeply furrowed gray-brown bark on the main trunk, and roughly triangular or heart-shaped leaves with coarsely toothed margins. The leaf stems are flattened. What is this tree?

Answer: Rio Grande Cottonwood (Populus deltoides subsp. wislizeni)

This combination of features—location in the bosque (riparian area), triangular/heart-shaped leaves, and flattened petioles (leaf stems) that cause the leaves to flutter in the wind—is classic for the Rio Grande Cottonwood.

You are called to a property in Albuquerque to identify a tree with compound leaves. Which of the following native New Mexico trees has pinnately compound leaves and is known for its showy, drooping clusters of pink, pea-like flowers in the spring?

Answer: New Mexico Locust (Robinia neomexicana)

While Boxelder and Velvet Ash have compound leaves, the New Mexico Locust is distinguished by its characteristic pea-like flowers arranged in large, drooping racemes. This species is a member of the legume family (Fabaceae) and often forms thorny thickets.

What is the primary visual difference between the needles of a Piñon Pine (Pinus edulis) and a Ponderosa Pine (Pinus ponderosa)?

Answer: Piñon needles are shorter and in fascicles of two.

The most reliable field identification difference is the needle arrangement and length. Pinus edulis has short needles (1-2 inches) grouped in fascicles of two. In contrast, Pinus ponderosa has significantly longer needles (typically 5-10 inches) that are usually found in fascicles of three (or sometimes two).