It’s early November and my Pachypodiums in the greenhouse are still in full leaf. In a few weeks the big geayi will start dropping its leaves, and once it does, the easiest way to tell it from a lamerei goes with them. So this is a good week to put the two next to each other.
These two get mixed up a lot. Both are tall, spiny-trunked Pachypodiums from Madagascar with leaves only at the top, and young plants of both are often sold side by side. I’ve had both for a few years now: one big P. geayi, bought around 2022 when it was already eight or nine years old, a large old P. lamerei, two P. lamerei var. ramosum, two lamerei seedlings of my own and six geayi seedlings. Below is what I look at to tell them apart. It’s all from my own plants, so don’t read it as a botanical key.
Leaf width and colour
On grown-up plants, lamerei leaves are about twice as wide as geayi leaves. (On seedlings it’s a different story, which I come back to further down.) My geayi has long, narrow leaves that hang out from the top almost like a fountain, and they’re a darker, muted green. Lamerei leaves are a lighter green, and with light behind them they look a little see-through compared with the geayi.
My two var. ramosum have leaves a bit wider than plain lamerei, and a touch lighter in colour. The difference is small, so I wouldn’t use it on its own to say which one you have.
How the spines sit
Both species have spines in groups of three, so counting them doesn’t help. What helps is how they sit. On my old geayi, all three spines in a group are thick and about equally strong, and they point upward along the trunk. On lamerei, one spine in each group is shorter, and the two longer ones stick out flat to the left and right. So from a bit further away, the spines on a lamerei seem to lie sideways around the trunk, and on a geayi they mostly point up.
Trunk colour and texture
My old lamerei has a slightly lighter trunk than the geayi, and the ramosums are lighter again. The texture is harder to put into words. The geayi’s skin is smoother, but the trunk itself is lumpier, with more bumps and dips under the spines. The lamerei’s surface is flatter but looks more worn, almost weathered. On seedlings I can’t see any difference in the trunk at all, so I don’t use it until the plants are a few years old.
Var. ramosum and branching
Ramosum is supposed to be the branching form of lamerei, and mine started branching early. I bought my two at about four years old, and one of them already had a small new branch, so the branching probably began at around three. None of my other seedlings have branched yet. My old lamerei has two heads too, but only because I cut it back years ago, so a branched lamerei isn’t automatically ramosum.
Telling geayi and lamerei seedlings apart
Seedlings were the hardest for me, because most of the differences above don’t show yet.
Young lamerei leaves are much narrower than on an old lamerei. They’re about as wide as the leaves on my grown geayi, and geayi seedling leaves are the same width. The colour is the same too: lamerei seedlings start out dark green, very close to the geayi seedlings, and only get lighter as they grow.
The only difference I can see is length. Geayi seedling leaves are longer, lamerei ones shorter. So if you have a tray of young Pachypodiums of the same age and don’t know which is which, look at leaf length, not width or colour. On my seedlings, the length difference showed after about 18–24 months.
Growing geayi and lamerei
Both have been easy. I haven’t lost a single geayi or lamerei, old or young, including the winters on my unheated balcony, which sat mostly at 5–10°C (41–50°F) and close to 0°C (32°F) for a couple of weeks. Neither has flowered yet, and I don’t expect flowers for another ten years or so.
They grow in similar mixes: my geayi seedlings are in about 70% mineral and 30% organic, and the big geayi in 80–85% mineral. The full recipes are in my soil mix post. The one real difference in care is winter leaf drop: my old geayi loses about 80% of its leaves, the old lamerei 40–50%. I wrote about that in last week’s post on why my Pachypodiums lose their leaves in winter.
What’s next
In spring I want to take a photo of a geayi and a lamerei seedling of the same age next to each other. I didn’t have anything like that when I started. Next week is something completely different: my Welwitschia mirabilis seedlings, from the 2024 and 2025 sowings.