Tuesday, 30 May 2017

Encountering Aliens

Before we have an Orson Welles type panic, these aliens are not out to destroy humanity and take over the planet (at least I don't think they are), these are invasive alien plants. Yesterday I spotted a weird-looking plant carpeting an area of overgrown grassland and recognised it as one of the Pirri-pirri-burs. I took a scrap of it indoors with me and with a bit of help from my trusty, if rather battered, copy of Stace figured it was Bronze Pirri-pirri-bur Acaena anserinifolia, a new one for me. Cool. I emailed a pic across to BSBI Recorder Stephen Bungard who was 'noncommittal' and suggested I keyed it through with Stace... Seems that most of the Acaena around this part of the world is Acaena inermis. Ok, no worries I'd try again tomorrow. Here's the image I sent to Stephen

So today I returned and grabbed several leaflets from different plants, a couple of flower heads and a few of the spiny seedheads, just in case the sample I'd taken yesterday was atypical. I also brought my copy of Poland into play since it uses a whole different suite of features to ID a plant. Between them I'd nail this sucker! Have to say, it still looked good for anserinifolia.

Habbo shot. It's the pale-headed stuff in the long grass
Entire plant, minus the roots
From Stace - Apical pair of leaflets 1.2-2.5x as long as wide, 5-12 teeth and 3-10mm long
From Poland - silky hairy beneath, stem brown
From Poland - Silky- or patent-hairy above (inermis is hairless on upperside)
From Stace - spines on hypanthium 2-4, barbed at apex (inermis is imperfectly/not barbed)
From Stace - hypanthium with up to 4 spines
Pro-anserinifolia features are as follows:

Apical leaflets are longer than wide with 9 teeth (about as long as wide on inermis)
Up to 4 spines on hypanthium (0 to imperfectly formed on inermis)
Spines are barbed (unbarbed on inermis)
Leaf is patent-hairy on upper surface (hairless on inermis)

The only thing I'm worried about is that it looks a lot like Acaena caesiiglauca which has longer spines (mostly 3.5-6mm for anserinifolia, those on my plant are nearer 8mm) and has a blue-green glaucous colour to the upperside of the leaves. In the wild my plant appears quite glaucous, indoors not so much. Google Imaging shows that my plant isn't really blue enough for caesiiglauca though. Acaena magellanica also has long spines, but that is hairless on the upperside of the leaves, is glaucous on both sides of the leaf and has green stems (Poland). 

So...I think I have Bronze Pirri-pirri-bur. Probably.

Moving on to the next alien plant, several weeks back I found a whole patch of muddy ground next to a stream covered in strange leaves. I didn't know what they were. When Stephen Bungard visited I asked him for help and he replied "Mimulus!" (the monkeyflower family). I've waited until today for the flowers to appear. Suddenly there were dozens upon dozens on show! 

Stunningly gorgeous (and variable) flowers, I figured the colour patterning was just too unstable for this to be Blood-drop-emlets. But at the same time clearly too heavily marked for Monkeyflower. So a hybrid, bugger. These plants readily hybridise and backcross and all sorts of other weird stuff and are notoriously difficult to pin down. Oh well, let's grab a whole plant and take it back indoors. What could possibly go wrong...

...some time later

I was failing to see all features in the Stace key. Even through a microscope I couldn't discern the necessary "simple white hairs inside the calyx". Poland's key was simplicity itself and led straight to Hybrid Monkeyflower Mimulus x robertsii but Stace had me scuppered. I couldn't progress past the "upper calyx tooth distinctly longer than the lower 4"

Upper calyx tooth larger than the others beneath it - check. Now what?
Ok, so was my plant fertile or sterile? That could help rule out some of the options. Peeling back the petals revealed the anthers to be bare of pollen! Er yeah, I think it's fair to say that it's sterile. 

Not even a dusting of pollen from what I can see
I was still worrying about small white hairs in the calyx. Then I re-read the couplet for the umpteenth time and realised I was being a twat. "Small simple white hairs present on inflorescence, at least ON KEELS OF calyx" ! Oh right, I'd been cross-reading the second part of the couplet which says "0 or very few simple white hairs except INSIDE calyx" Taking a look at the calyx keels I could see a row of very short white hairs. Bloomin' 'eck Seth! So, following the key to it's conclusion it seemed that Stace agreed with Poland and my plant was indeed Hybrid Monkeyflower Mimulus x robertsii. The BSBI Map shows that it occurs over much of Skye which is reassuring. 

Next stage was internet searches, just to see that my plant matches (ie that Mimulus isn't actually a low growing alpine!) and I came across this brilliant site. Scrolling down the screen was this table

Those pesky simple white hairs running along the calyx keels differentiate robertsii from smithii, I like it when loose ends are tied up. That's not to say the plants in Uig Woods aren't backcrossed or further hybridised, but I'm happy to record them as Hybrid Monkeyflower which, along with the Bronze Pirri-pirri-bur, is also new for me and is my 1100th species of vascular plant on my PSL.

Now I just need a real botanist to read this and rip it all to shreds...

EDIT: See comment below - The man from Del Raasay he say "Yes!" And a first for VC104 too, happy days :)


  1. A "Real Botanist" responds.... Yes I agree on both counts, Acaena & Mimulus. And pleasingly, I have just checked the rampant Raasay Acaena using John Poland's key and it is what I have called it for years, A. inermis. Leaves hairless above but hairy on veins below. A. anserinifolia is new to the vice-county. Best, Stephen

  2. Where are your stomata measurements? Maybe you don't have a graticule yet ...

  3. Maybe I don't have the dye either... ;) Actually, now I've started to look at fungi spores I really should get myself a graticule. "looked quite small even at 400x" probably won't sway the judges decision in my favour if I ever find a goodun.