Glossary – Tree Architecture Terms
This page is under construction. It compiles key terms from the major books and articles on tree architecture, selected to help arborists, students, scholars, and researchers orient themselves in the field. The definitions are drawn from the following works:

• Tropical Trees and Forests – An Architectural Analysis (Hallé, Oldeman & Tomlinson, 1978)
• Mais d’où viennent les plantes (Hallé & Keller, 2019)
• The Trees and the Forest (Vester, 1997)
• La Taille des Arbres d’Ornement (Drénou, 1999, 2015, 2021)
• La taille de formation des arbres d’ornement (Boutaud, 2003)
• L’architecture des arbres des régions tempérées – son histoire, ses concepts, ses usages (Millet, 2012, 2022)
• Face aux Arbres (Drénou, 2009, 2019)
• « Parlez‑vous Archi ? » Les principales définitions de la méthode Archi (Drénou & Caraglio, 2019)
• „¿Hablamos Archi?“ Principales definiciones del método Archi (Drénou & Caraglio, 2018)

As the glossary is completed, individual terms and definitions will be added here, with short explanations based on these texts.

A

Absolute branch order — see branch order, absolute. (5)

Actinomorphic — radially symmetrical. (5)

Anemochores — plants with wind-dispersed propagules. (5)

Apparent branch order — see branch order, apparent. (5)

Apposition growth — see growth, apposition. (5)

Architectural tree model — see model. (5)

Architecture — the visible, morphological, expression of the genetic blueprint of organic growth and development. (5)

Articulated growth — rhythmic growth which results in shoot units separated by morphological discontinuities, e.g., bud-scale scars. (5)

Articulated shoot — shoot produced by articulated growth, usually with distinct bud-scale scars. (5)

Axis — supporting part of an organ or complex, e.g., leaf axis, stem. (5)

Axillaire — se dit d’un organe situé à l’aisselle d’un autre. (2)

B

Bamboo — a member of the subfamily Bambusoideae, Gramineae. (5)

Bamboo habit — distinctive architecture as exemplified by a bamboo. (5)

Bayonet-joint — articulation, usually in orthotropic shoots, where substitution growth has occurred. (5)

Biomass — dry or wet weight of organic matter produced by growth of an organism. (5)

Biotope — the living space occupied by an organism. (5)

Branch order — the numerical sequence of an axis. (5)

Bud — the shoot apical meristem and its immediate derivatives. (5)

Bud complex — a group of closely juxtaposed buds. (5)

Bud-scale — a modified leaf or other organ enveloping and protecting a resting bud. (5)

C

Cauliflory — production of flowers on the trunk. (5)

Chablis — a gap in the forest produced by the fall of a tree. (5)

Colleter — secretory, usually nonvasculated organ associated with a bud. (5)

Continuous growth — growth without visible rhythm producing shoots without distinct articulations. (5)

Corner’s rules — axiomatic rules governing branching frequency and axis-appendage correlations in relation to axis size. (5)

Crown area index — total projected crown area above unit area of ground surface. (5)

Cryptocotylar germination — see hypogeal germination. (5)

Cryptogeal germination — germination in which the plumule is buried by late extension of the cotyledonary axes. (5)

Cyclophysis — the organizational status of a meristem in a tree determined by its age. (5)

D

Decussate (leaf) arrangement — in pairs, the successive pairs at right angles. (5)

Dedifferentiation (of axes) — change from one level of differentiation to a previous, younger, level. (5)

Dendrochronology — determination of historical events on the basis of annual growth increments in tree trunks. (5)

Diaspore — a unit of dispersal. (5)

Distichous (leaf) arrangement — alternate, but restricted to a single plane. (5)

Dryad — a high forest tree occupying a precise ecotope. (5)

E

Ecological inversion point — the point in the forest where real vertical microclimatic gradients cross the average vertical gradient. (5)

Ecological inversion surface — collective microclimatic inversion points. (5)

Ecotope — combination of niche and habitat occupied by a plant. (5)

Emergent — an isolated tree standing above the average forest canopy. (5)

Energy flow — transfer of energy within the tree or between the tree and its environment. (5)

Epicormic — originating from the trunk, as in an epicormic shoot developing from a latent meristem. (5)

Epicotyledonary axis — stem immediately above the cotyledonary node. (5)

Epigeal germination — in which the cotyledon(s) escape from the seed coat and usually appear above ground as photosynthetic organs. (5)

Episodic growth — rhythmic growth. (5)

Epitrophy — generalized response leading to the formation of erect axes. (5)

Establishment growth — post-seedling growth of plants, usually without secondary thickening meristems. (5)

F

Flush — rapid primary shoot expansion and elongation. (5)

G

Growth habit — the ultimate form of a plant as expressed in its physiognomy. (5)

Habit — see growth habit. (5)

Habitat — the community environment. (5)

Hapaxanthy — development of an axis which is determinate by terminal flowering. (5)

Heliophilous nomad — see nomad, heliophilous. (5)

Heteroblastic — with a morphological difference between juvenile and adult. (5)

Homeostasis — in an ecological sense, a community in a steady state. (5)

Homeostatic forest — a forest in a condition with minimum free energy. (5)

Hypogeal germination — in which the cotyledon(s) remain within the seed coat and usually do not appear above ground as photosynthetic organs. (5)

Hypopodium — the part of a branch between its origin and its first leaf. (5)

H

Habit — see growth habit. (5)

Habitat — the community environment. (5)

Hapaxanthy — development of an axis which is determinate by terminal flowering. (5)

Heliophilous nomad — see nomad, heliophilous. (5)

Heteroblastic — with a morphological difference between juvenile and adult. (5)

Homeostasis — in an ecological sense, a community in a steady state. (5)

Hypogeal germination — in which the cotyledon(s) remain within the seed coat and usually do not appear above ground as photosynthetic organs. (5)

Hypopodium — the part of a branch between its origin and its first leaf. (5)

I

Infrastructural complement — the population of latent meristems in a forest, representing potential growth. (5)

Infrastructural set — the population of functioning meristems in a forest, representing actual growth. (5)

Initial complex — the visible complex of axes and active meristems produced by a tree when growing precisely according to its model. (5)

Intermittent growth — noncontinuous growth without the predictable regularity of rhythmic growth. (5)

Inversion point, ecological — the point in the forest where real vertical microclimatic gradients cross the average vertical gradient. (5)

Inversion point, morphological — the insertion of the lowest major limb of a tree above which all branch or reiterative complexes are progressively smaller. (5)

Inversion surface, ecological — collective microclimatic inversion points. (5)

Inversion surface, morphological — collective inversion points of individual trees in a forest. (5)

J

Jeune plant — végétal au début de son développement. (1)

K

K selection — selective conditions which favor longevity of individuals at expense of reproductive capacity. (5)

K strategist — a species adapted to maximum survival of individuals at expense of reproductive capacity. (5)

L

Lammas shoot — late season flush of growth in a temperate tree which normally flushes annually. (5)

Leaf area index — cumulative projection of leaf area above unit ground area. (5)

Leptocaul — a thin-twigged and usually much-branched tree. (5)

Linear sympodium — a single stem made up of successive, usually determinate, monoaxial units. (5)

Long shoot — where there is shoot dimorphism, an extended shoot contributing to the architecture of a tree. (5)

Long shoot — where there is shoot dimorphism, an extended shoot contributing to the architecture of a tree. (5)

Linear sympodium — a single stem made up of successive, usually determinate, monoaxial units. (5)

1. Boutaud, J., 2003. La taille de formation des arbres d’ornement. Société française d’arboriculture.
2. Drénou, C., 2009, 2019. Face aux arbres. Apprendre à les observer pour les comprendre, Paris, Ulmer.
3. Drénou, C., 1999. La taille des arbres d'ornement.
4. Hallé, F. and Keller, R., 2019. Mais d'où viennent les plantes ? Actes Sud.
5. Hallé, F., Oldeman, R.A. and Tomlinson, P.B., 2012. Tropical trees and forests: an architectural analysis. Springer.
6. Millet, J., 2012. L’architecture des arbres des régions tempérées: son histoire, ses concepts, ses usages. Éditions MultiMondes.
7. Vester, H.F.M., 1997. The Trees and the Forest-The role of tree architecture in canopy development; a case study in secondary forests (Araracuara, Colombia).