x4 images. Double click to enlarge.
These extraordinary growths are caused by a miscroscopic mite called Eriophyes tiliae, and it is commonly known as the Red Nail Gall Mite.
They appear on the upper surface of the leaves of Large-leaved Lime (Tilia platyphyllos) and the hybrid Common Lime(Tilia x europaea). I found this tree in a local park covered in them.
x2 images. Double click to enlarge.
Not quite the mythical Gorgon that would turn you to stone with one glance, but that fungi gall again, Gymnosporangium sp, but now more developed and in the throughs of spreading itself around.
I believe these are the telial horns, the spore tubes, and they are opening up and releasing spores.
x4 photographs. Double click to enlarge.
The Hawthorn bush at the bottom of my garden is really showing up some oddities this year. I noticed some rust spotting, larger than the usual, on the upperside of the leaves on the main and secondary veins, and when I flipped them over this was underneath.
They were tricky to photo because of all the sticky out points, so I tried my hand at some photo stacking. The above images are made up of up to 3 stacks each, and could have done with more really. Difficult to do handheld, but possible.
This is the upperside of the leaf which looks like it has rusty pimple. So what do we have here? Well, it’s a plant gall, a fungi called Juniper Rust (Gymnosporangium sp.), and you may wonder what is it doing on Hawthorn?
It has a complicated lifecycle, beginning with Junipers, its main host. Fungus forms a ball on Junipers which produces a set of orange tentacle-like spore tubes called telial horns. These horns expand and have a jelly-like consistency when wet. The spores are released and travel on the wind until they infect the secondary hosts like Hawthorn where fungus produces tiny rust-like pimples on the leaves. It also infects the fruit, which grows tubes which carry the spores. The spores must then infect a Juniper to complete the life cycle.
Andricus foecundatrix – Another gall which forms on oaks. The asexual generation of the Artichoke Gall Wasp (Andricus foecundatrix) is responsible for causing these galls which grow from Pedunculate Oak (Quercus robur) or Sessile Oak (Quercus petraea) leaf buds. Also called the Hop Gall, a single larva develops within the gall to maturity in August, when it falls from the tree for pupation to take place during the winter. In spring the adult wasps emerge to lay eggs in oak catkins, from which the sexual generation will eventually emerge.
Knopper Gall (Andricus quercuscalicis) – These odd growths on the acorn are caused by a tiny wasp called Andricus quercuscalicis. It has quite a complicated lifecyle, so please stay with me. The agamous (asexual) generation develop within the galls on the acorns of various oaks including Pendunculate Oak (Quercus robur) and Sessile Oak (Quercus petraea) as larvae. The galls fall from the trees in late summer, and the adult gall wasps will emerge the following spring, although some may remain within the galls for up to four years. Eggs are then laid in Turkey Oak (Quercus cerris) buds which result in tiny cone-shaped galls on the male catkins. It is here the sexual generation develop, and when they become adults the cycle repeats itself.
Silk Button Gall Wasp (Neuroterus numismalis) – On your travels have a look out for these clustered on the underside of oak leaves. Each gall contains the larva of the wasp. The last image shows what the top of the leaf looks like.
Robin’s Pincushion (Diplolepis rosae) – Also called the Bedeguar Gall, this strange but beautiful, almost alien, fibrous growth is caused by the larvae of a tiny wasp. It is found on the stems of wild roses, and each of these can contain many grubs which feed on the plant tissues inside a woody heart filled with chambers, but apparently do the plant no serious harm.
I am fascinated by plant galls, which often go unnoticed, and how organisms like wasps, flies, mites and even fungi, can transform living tissue into these abnormal, often bizzare forms.
Double-click image for a closer look.
Aceria macrorhyncha – You may have noticed these little bright red pustules on the upper surface tree leaves and wondered what they were? These are plant galls, and this one in particular is caused by a tiny mite ( they belong to the same group as spiders) which feed on the leaves of Sycamore (Acer pseudoplatanus). The mites are small enough to pierce and feed on individual plant cells, causing the surrounding cells to enlarge and multiply to form the gall. In the final image you can see the holes on the underside of the leaf, beneath the galls. Not sure what the red jelly-like stuff is. Double-click images for a closer look-see.
© Peter Hillman ♦12th May 2020 ♦ Local woodland path, South Staffordshire ♦ Nikon D7200
This small fist-like ball on the end of this fern frond is caused by a fly called Chirosia grossicauda. The larvae tunnel into the central veins of the pinnules in late summer and cause them to roll downwards from the tip. The solitary white maggot feeds on the main vein by mining. Mature larvae most likely pupate in their galls. Widespread and fairly frequent in Britain.
Photographs of Chirosia grossicauda taken June 2014, local woodland margin, Staffordshire. © Pete Hillman 2014. Camera used Nikon D3200, with Sigma 105mm macro lens.
I have always been fascinated by these strange yet sometimes most beautiful growths. Plant galls are something of an oddity when some folk first encounter them, others don’t even know they exist. Plant galls come in all shapes and sizes, and are formed by another organism using the plant as a host, using it for shelter and for food.
They are caused by insects or mites, fungi or bacteria, and cause a biological reaction within the plant which causes these odd lumps and bumps to form of their tissues. They affect both herbaceous and wood plants, and there are at least over 1,000 species in Britain alone.
It is most unlikely you would see the mite or insect which causes the majority of these galls for they are very small, some even microscopic, but the species can be identified by the galls they produce.The study of plant galls is called cecidology.
A tiny mite produces the pimple-like spots on the leaves of Field Maple (Acer campestre). Each pustule measuring between 1-3mm high may contain several mites. The galls maybe fairly prolific, covering leaves almost in their entirety.
The mites leave the gall through tiny holes in the underside of the leaf in autumn and overwinter in fissures in the tree bark.
Seen summer until autumn. Common and widespread.
Photographs of Aceria myriadeum, taken June 2013, local wood and nature reserve. © Pete Hillman 2013. Camera used Nikon Coolpix P500.
This is a mite which produces tiny red pustule galls on the upper surface of Common Alder (Alnus glutinosa). They are up to 2mm in diameter, and are green to begin with, becoming red or purple later on. They may cover the whole upper surface of the leaf, and in some cases this may prohibit growth of the leaf.
The mites leave the gall via a small hole beneath the leaf which it had originally entered by in autumn. It sees the winter through in empty cones and bark crevices.
Seen summer until autumn. Common and widespread.
Photographs of Eriophyes laevis, taken June and 2013, local wood and nature reserve. © Pete Hillman 2013. Camera used Nikon Coolpix P500.
This is a mite which produces felt-like galls on the surface of Sycamore (Acer pseudoplatanus) tree leaves. On the top side of the leaf the gall is like a blister which is usually yellowish to begin which then turns brown, and underside it is cream or yellowish when fresh, browning as it ages.
The mites leave the gall in which they shelter and feed on the leaf in the autumn and overwinter in the twigs and branches.
Seen summer until autumn. Common and widespread.
Photographs of Sycamore Felt Gall (Aceria pseudoplatani), taken June 2013, local wood and nature reserve. © Pete Hillman 2013. Camera used Nikon Coolpix P500.
These marble like galls measuring up to 25mm in diameter are found beneath the leaves of Pedunculate Oak (Quercus robur) and Sessile Oak (Quercus petraea). Cynips quercusfolii is a tiny black gall wasp, and within the plant gall its larva stage grows. On Pedunculate Oak the gall is smooth where on Sessile Oak it is rough and warty. They start off as yellowish-green, turning pink then red towards autumn. It turns brown just before the leaves fall.
The gall and the wasp larva inside matures on the ground and the adult wasp emerges between late autumn and early spring. Eggs are laid in the dormant oak buds where small purple galls are formed. These will bring forth the sexual generation which emerge in late spring and lay their eggs in the new season’s leaves to start the process over again. Seen summer until autumn. Common and widespread.
Photographs of Cherry Gall Wasp (Cynips quercusfolii), taken June and October 2013, local wood and nature reserve. © Pete Hillman 2013. Camera used Nikon Coolpix P500.
This strange yet beautiful growth is the result of a tiny gall wasp called Diplolepis rosae laying its eggs in a wild rose bud in springtime. Also called the ‘Bedeguar Gall Wasp’, the females appear in the spring just in time to lay their eggs in the fresh young buds. Males are a rarity, and most females lay fertilised eggs without mating.
The gall mainly grows on the stem of the plant, and it can spread up to 7cm across. The gall has a woody core each surrounded by branching red or green hairs. The core usually has multiple chambers in which each a wasp larvae develops. The galls turn brown in the autumn and lose many of their hairs.
Photograph of Robin’s Pincushion (Diplolepis rosae), taken August 2010, country park, Staffordshire. © Pete Hillman 2010. Camera used Panasonic Lumix DMC-FZ38.
Whilst on a walk through a local churchyard I noticed these fine old Turkey Oaks (Quercus cerris) in the grounds. I saw all these strange knobby growths on the acorns. I took these series of photographs, and although I knew they were a plant gall of some kind, I later identified them as the Knopper Gall, which is caused by a tiny wasp. The asexual generation of Andricus quercuscalicis develops on the acorns causing the formation of the galls. Green and sticky to begin with, the galls eventually flush red and then turn brown and woody.
The galls fall from the trees in late summer, and the adult gall wasps will emerge the following spring, although some may remain within the galls for up to four years. Eggs are then laid in Turkey Oak buds which result in tiny cone-shaped galls on the male catkins. The Knopper Gall arrived in Britain in the 1960s, and it did cause some alarm at first. It can be extremely abundant in some years (the trees I saw were completely covered) but there are usually enough acorns left for the trees to survive.
Photographs taken August 2013, local churchyard, Staffordshire.
Nature Journeys 