The Jimenez Matrix
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The Jimenez Matrix
The Matrix was developed by Dr. Humberto Jimenez Saa as a way of teaching dendrology, the science of tree identification, to students of all levels. It builds upon early work by Dr. Leslie Holdridge, a pioneer in tropical forestry and tropical ecology, aimed at elucidating plant families using only vegetative material. In tropical forests, leaves and bark are almost always available, but flowers and fruits are seasonal and often hidden from those of us who cannot access the canopy the same way as a monkey, bird, or bee. Traditional plant identification and classification is based on flowers which are readily available to most temperate zone botanists, but not easily accessible in most tropical forests.
Strictly speaking, The Matrix is not a taxonomic key. It does not set out to identify any and all plant specimens. It doesn’t even claim to work all the time. BUT it works MOST of the time and is relatively easy to use once you learn some basic terminology and agree to follow the routine described in How To Examine A Plant.
Using the matrix…
The Matrix consists of eight sections and can fit on a mere 6 pages. Each section is based upon phyllotaxy (alternate, opposite, or whorled), leaf type (simple or compound), and the presence or absence of stipules. Once these three basic pieces of information have been determined, it is a matter of identifying the combination of two or three other traits that allow you to determine the family to which a plant belongs. So get yourself a branch with some leaves on it and follow the routine until you can assign your specimen to the proper family.
Please note that The Matrix is not complete. Each user may develop his or her own version of the matrix utilizing features that are easily remembered or observed by the user. As your botanical knowledge increases, you will certainly want to expand the matrix to accommodate your expanding list of plant families and genera. The Matrix presented here was constructed by Scott Shumway with the help of Dr. Jimenez-Saa as part of a course in Tropical Dendrology. The Matrix may be reproduced, but Dr. Humberto Jimenez-Saa should be properly credited as its creator. Please note that this matrix is restricted to dicots. In the future I hope to add a section for monocots.
About Dr. Humberto Jimenez-Saa
To truly appreciate the beauty of The Matrix and to master it, you should take one of the Tropical Dendrology courses offered by Dr. Humberto Jimenez-Saa.
Dr. Humberto Jimenez-Saa is an inspirational teacher. His deep connection to and passionate love of trees is infectious. It is hard to imagine anyone with a greater knowledge of tree identification. As a teacher, he is firmly committed to sharing this knowledge with his students or anyone with an interest in trees. After studying with Humberto, you will have a newfound appreciation for every tree, leaf, or stipule that you encounter anywhere in the world. His love of trees and zeal for teaching is matched by a love of life and hope for the future of humanity. He measures his remaining time on Earth by the need to identify and label as many plants as possible, and freely admits that he has at least another 50-60 years left before his work will be complete. Until then, he will continue to tell us “here’s another tree for you to study…”
Dr. Jimenez' dendrology website is located at: http://www.hjimenez.org/dendrology.html
THE MATRIX
-The following matrix was prepared during the Tropical Dendrology course taught by Dr. Humberto Jimenez-Saa in 2008 in Costa Rica.
Key to the eight sections of the matrix based on phyllotaxy, leaf type, and stipules.
- Alternate – Simple Leaves – No Stipules
- Alternate – Simple Leaves – With Stipules
- Alternate – Compound Leaves – No Stipules
- Alternate – Compound Leaves – With Stipules
- Opposite Or Whorled – Simple Leaves – No Stipules
- Opposite Or Whorled – Simple Leaves – With Stipules
- Opposite Or Whorled – Compound Leaves – No Stipules
- Opposite Or Whorled – Compound Leaves – With Stipules
1. ALTERNATE – SIMPLE LEAVES – NO STIPULES
| Turpentine odor, juvenile lvs red, resin dries dark, Ex: Anacardium, Mangifera | Anacardiaceae |
| Distichous, ranalean odor, string bark, pagoda branching, fibers in live bark, Ex: Annona, Xylopia | Annonaceae |
| Petioles of varying lengths, little horns at base, Ex: Dendropanax, Oreopanax | Araliaceae |
| Obovate lvs clustered at branch tip, sympodial branching, buttresses, Ex: Terminalia | Combretaceae |
| Rank odor, wavy leaf margins, pointy buds, irregularly flattened twigs, 1-seeded berry ± cupule, Ex: Nectandra, Ocotea | Lauraceae |
| Pseudoterminal stipule, brown black dots (lines), Ex: Ardisia | Myrsinaceae |
| Swollen nodes, rat-tail inflorescence, odor, Ex: Piper, Peperomia | Piperaceae |
| Citrus odor, pellucid dots, crenate margins, (spines), falsely simple, Ex: Citrus | Rutaceae |
| Simple & compound, bad tuna odor | Roupala (Proteaceae} |
| 3-veined common, perma-press, irregular margins, abundant pith | Asteraceae |
| Pseudo-opposite, anisophylly, rank odor, * hairs, (spines) | Solanaceae |
| 3-way branching: 2 horiz + 1 shorter vert, swollen nodes, Ex: Cordia | Boraginaceae |
| White or watery latex, coleters, paired fruits, Ex: Thevetia, Plumeria | Apocynaceae |
| Raspy leaves both sides, 2° veins parallel, reddish bark, mostly lianas, bejucos de agua | Dilleniaceae |
| Distichous, ranalean odor, myristicaceous branching, large seed & red aril, Ex: Virola | Myristicaceae |
2. ALTERNATE – SIMPLE LEAVES – WITH STIPULES
| Petioles of varying lengths, intrapetiolar stipule | Araliaceae |
| Bilobed leaves, like hoof of a deer | Bauhinia (Caesalpinioideae} |
| Watery latex, nectaries on upper petiole | Sapium (Euphorbiaceae} |
| Serrate, stellate hairs, long string bark, mucilage | Malvaceae sensu lato |
| White latex, terminal stipule, annular scars, syconium | Ficus (Moraceae) |
| Sheathing petiole, swollen node, rat-tail infl, odor, terminal stipule, Ex: Peperomia, Piper | Piperaceae |
| Distichous, serrate, uneven lf bases, scabrous one-way, string bark, narrow buttresses, Ex: Trema, Celtis | Ulmaceae |
| Serrate, (distichous), 3° veins parallel & perpendicular to 1°, pellucid dots & dashes, stipules inconspicuous, Ex: Laetia | Flacourtiaceae |
| Large terminal stipule, leaving scars | Cecropiaceae |
| Palmately lobed, peltate, terminal stipule, annular scars, hollow stems with ants, food bodies at base of petiole | Cecropia |
| Palmately lobed, NOT peltate, terminal stipule, annular scars, 3° veins parallel, stilt roots | Pourouma |
| Ovate, inclined stipule scar, 3° veins parallel | Coussapoa |
| Watery latex, nectaries at base of leaf, stellate hairs, senescent leaves red, 3-chambered fruit | Croton (Euphorbiaceae} |
3. ALTERNATE – COMPOUND LEAVES – NO STIPULES
| Imparipinnate, turpentine odor, juvenile lvs red, resin dries dark, Ex: Spondias | Anacardiaceae |
| Palmate, petioles of varying length, little horns at base, Ex: Schefflera | Araliaceae |
| Paripinnate, garlic odor and domatia (odorata), 5-chambered capsule | Cedrela (Meliaceae) |
| Parapinnate, terminal bud on rachis like a half open fist, thickened petiolule | Guarea (Meliaceae) |
| Imparipinnate, leaflet (5-7) size increases toward apex, terminal leaflet cuneate | Trichilia (Meliaceae) |
| Paripinnate, terminal bud shaped like pineapple plant | Swietenia (Meliaceae) |
| Parapinnate, large leaves, distinct texture, large fruit (4-angled capsule) | Carapa (Meliaceae) |
| Citrus odor, pellucid dots, crenate margins, (spines), Ex: Zanthoxylum | Rutaceae |
| Simple & compound, bad tuna odor | Roupala (Proteaceae} |
| Imparipinnate, leaflets alt, bitter taste, Ex: Simarouba | Simaroubaceae |
| Imparipinnate (mostly), serrate, leaflets asymm, grooves on petiole and twig, aborted prolongation on rachis, trees & lianas | Sapindaceae |
| Imparipinnate, petiolule thicker than rachis | Papilionoideae (FAB.) |
| Bipinnate with nectaries | Mimosoideae (FAB.) |
| Bipinnate without nectaries | Caesalpinioideae (FAB.) |
| Imparipinnate, swollen rachis between leaflets, turpentine odor, resin dries white, Ex: Protium, Bursera | Burseraceae |
| Imparipinnate, swollen rachis, bitumid petiole, strong turpentine odor, buttresses common, fr reddish | Protium Burseraceae |
4. ALTERNATE – COMPOUND LEAVES – WITH STIPULES
| Petioles of varying lengths, intrapetiolar stipules, palmate or tri | Araliaceae |
| Bifoliate: Hymenaea, Cynometra, Peltogyne, Macrolobium | Caesalpinioideae (FAB.) |
| Paripinnate with nectaries, ± winged rachis: Inga | Mimosoideae (FAB.) |
| Paripinnate ± fingerlike nectaries: Senna, Cassia | Caesalpinioideae (FAB.) |
| Paripinnate, NO nectaries | Caesalpinioideae (FAB.) |
| Trifoliate, stipels, ± spines: Erythrina | Papilionoideae (FAB.) |
| Bipinnate with nectaries | Mimosoideae (FAB.) |
| Bipinnate without nectaries | Caesalpinioideae (FAB.) |
| Note: bipinnate Fabaceae may lack stipules |
5. OPPOSITE OR WHORLED – SIMPLE LEAVES – NO STIPULES
| Swollen nodes, stipular ridge, anisophylly, mostly herbs | Acanthaceae |
| Sympetalous, zygomorphic, 4 stamens, ovary superior on fleshy disc, Ex: Crescentia | Bignoniaceae |
| Yellow of creamy latex, 2° veins parellel, thick leaves, “la cosa” sheltering of terminal bud, Ex: Clusia | Clusiaceae |
| Orange latex, terminal bud lance-shaped, ovate lvs, flattened stems | Vismia (Clusiaceae |
| Curvinerved veins, scalariform 2° veins (ladder-like), Ex: Conostegia, Miconia | Melastomataceae |
| Twigs square, (nectaries at leaf base), Ex: Stachytarpheta | Verbenaceae |
| Guava odor, pellucid dots, peripheral veins converge to form marginal vein, Ex: Psidium, Eugenia | Myrtaceae |
| 3-veined common, perma-press, irregular margins, abundant pith | Asteraceae |
| White or watery latex, coleters, paired fruits, Ex: Stemmadenia | Apocynaceae |
6. OPPOSITE OR WHORLED – SIMPLE LEAVES – WITH STIPULES
| Interpetiolar stipules, opposite or whorled, entire margins, Ex: Hamelia, Psychotria, Warszewiczia | Rubiaceae |
| Round interpetiolar stipules, montane forest trees | Cunoniaceae |
| Intrapetiolar stipule, T-shaped hairs, large oil-secreting glands on sepals, ungulate petals, trees & lianas, Ex: Byrsonima | Malpighiaceae |
| Free stipules, opposite or 3-whorled, marginal collecting vein, long. ridges, bark soft and breakable, Ex: Vochysia | Vochysiaceae |
7. OPPOSITE OR WHORLED – COMPOUND LEAVES – NO STIPULES
| Sympetalous, zygomorphic, 4 stamens, ovary superior on fleshy disc, trees & lianas, Ex: Jacaranda, Tabebuia | Bignoniaceae |
| Bipinnate, terminal leaflet larger, blue flowers | Jacaranda (BIGNON) |
| Palmate, 5-leaflets, yellow or magenta flowers | Tabebuia (BIGNON) |
| Palmate, 5-9 leaflets | Godmania / Cybistax (BIGNON) |
| Imparipinnate, orange flame flower, African tuliptree | Spathodea (BIGNON) |
| Palmate, 3-leaflets (4,5), square stem | Vitex (Verbenaceae) |
8. OPPOSITE OR WHORLED – COMPOUND LEAVES – WITH STIPULES
| Imparipinnate, winged rachis, interpetiolar stipule | Cunoniaceae |
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