Table of Contents
Trichocereus Species & Identification Guide
Identifying Trichocereus (San Pedro and its relatives) is genuinely hard: the popular species intergrade, look different young vs mature, and change with sun, water and age. This guide covers the main columnar species growers deal with, with the features people actually use to tell them apart — and example photos from our own clone archive.
Quick comparison
| Species | Ribs | Spines | Epidermis | Habit |
|---|---|---|---|---|
| T. pachanoi | 6–8, broad | short / sparse | mid-green, matte | fast, tall columns |
| T. peruvianus | 6–9 | longer, stouter | often glaucous/blue | erect to leaning |
| T. bridgesii | 4–8 (often 4–6) | often long, needle-like | light green | slender columns; TBM/crest forms |
| T. macrogonus | 7–9, robust | stout | strongly glaucous | thick columns |
| T. scopulicola | 4–6 (often 5) | ~spineless | glossy, smooth | smooth “melting” columns |
The species
- T. pachanoi — San Pedro / Huachuma. The common, fast, near-spineless one.
- T. peruvianus — Peruvian Torch. Spinier and often bluer; hugely variable.
- T. bridgesii — Bolivian Torch / Achuma. Fewer ribs; famous monstrose (TBM) and crested forms.
- T. macrogonus — robust, glaucous; the senior name now absorbing much of peruvianus/pachanoi.
- T. scopulicola — “Scop”. Smooth, glossy, near-spineless; a favourite hybrid parent.
How to identify (in practice)
Work through, in rough order of usefulness:
- Rib count — count around the column at a mature section (few = bridgesii/scop; many/broad = pachanoi/macrogonus).
- Spines — length, thickness and colour (sparse/short = pachanoi/scop; long/stout = peruvianus/bridgesii).
- Epidermis — matte green vs a glaucous blue bloom (peruvianus/macrogonus lean blue).
- Areoles — spacing and the “notch” above them (pachanoi often notched; bridgesii widely spaced).
- Habit and growth — speed, thickness, leaning, and any monstrose/crested growth (bridgesii).
Remember: growing conditions and age shift all of these, and a single clone is not proof of a species. For certainty you need flowers or DNA — treat photos as pointers.
A note on taxonomy
The names here follow common horticultural / collector usage. Formal taxonomy is contested and has been repeatedly revised — several of these “species” are treated by modern authors as varieties of T. macrogonus, and wild populations grade into one another. This guide aims to help you communicate and narrow down, not to settle taxonomy.
Part of the Trichocereus Species & ID Guide. This is a horticultural ID reference, not definitive taxonomy — Trichocereus species intergrade and their classification is debated. Example photos are community-submitted clones from our archive; click a clone for its page.