The Basal Eudicots, Part1: The Papaveraceae

Spring is nigh, and you may have noticed a lot of bright flowers sticking their sleepy heads out. Which is great for Botanists, as it means the identification season is now beginning.

This post will be about 'The Basal Eudicots'. This group of plants are what taxonomists think of as the base, or diverging group of the Eudicotyledons which you may have been taught as the “Dicots”. The reason for the name change was to differentiate between ALL the dicots, which includes the early angiosperms I wrote about in my last post e.g. the waterlilies, and modern dicots, which is everything else that flowers excluding the monocots. You could say that 'the dicots' now refer to an all-encompassing group of the palaeo-dicots and the eudicots.

So now that we have that cleared up I can tell you about the basal eudicots. As the name suggests, and as I've hinted at already, they are at the base of the evolutionary tree of the eudicots. You could say they are the middle-men, or the transition zone between the old and the new.

The angiosperm evolutionary tree. The Basal Eudicots sit between the Basal Angios and the rest of the Eudicots (Asterids and Rosids)

This is evident in their flower morphology as they share common characters between the basal angiosperms and the more evolved eudicots. They tend to have open (i.e. un-fused) petals, dimerous (i.e. flower parts in twos or fours) which is a basal character as well as pentamerous (i.e. flower parts in fives) which is a higher character. They also have taxa that have undifferentiated petals and sepals (i.e. tepals) which is a basal character and some that have clear differentiation between the petals and sepals (higher ch.), and are generally actinomorphic (i.e. flowers have many planes of symmetry) but of course there are always exceptions!

Papaver and Ranunculus are examples two species in the basal eudicots that have open flowers with tetramery (4 petals in the poppy) and pentamery (5 petals in the buttercup). Photo from edenbrothers.com and wikipedia.com respectively.

The relationship of the families in the Order Ranunculales.
The Papaveraceae (green)  is the most basal in this Order.
Modified from Mobot.org

The Papaveraceae, the most basal family of the Ranunculales, contains a genus we are all familiar with in Ireland: the poppies.

Members of the Papaveraceae can be recognised by their flowers, which have 2 sepals and 4 petals. Unfortunately, it is likely that no members the Papaver genus are native to Ireland, with many found in the wild being garden-escapes. However, they are becoming rarer in Ireland as the landscape has changed over the years, and they prefer to grow on loose, sandy soil.

Papaver rhoeas, the corn poppy, which is common in fields across Europe. This poppy is a
symbol used on Remembrance day in the UK. wikipedia.commons.org

Papaver somniferum, the opium poppy, originally from Turkey, it has been
introduced into many countries worldwide for its medicinal uses. wikipedia.commons.org

 Meconopsis cambrica or the Welsh Poppy is the most similar truly native species to what we recognise to a poppy, except they have large yellow petals instead of red. It grows in damp shady places in the mountains, and is pretty rare, but can also be found elsewhere as a garden-escape. 

Meconopsis cambrica, the Welsh Poppy likes to have its feet wet.
 Photo from overthegardengate.co.uk

Distribution of the Welsh Poppy in the British Isles. Note it is quite rare in Ireland, but very widespread in the UK. Map from BSBI.org

Fumaria is another common genus of the Papaveraceae with members found in Ireland. They used to be in a family of their own as they looked so different from Poppies but recent genetic studies placed them within the Paps, and re-classified them as a sub-family, the Fumaroideae. Interestingly, they have zygomorphic or irregular flowers i.e. they have only one plane of symmetry, unlike the rest of the basal Eudicots, as their petals fuse into weird shapes- these guys are the exception! You may recognise the flamboyant flowers of the plants known as “bleeding hearts” pictured below. Similar to Papaver, they are all non-native, and are likely to be found in the wild as garden escapes. There are 6 species found in Ireland. 

Bleeding hearts, or Lamprocapnos spectabilis is a native of East-Asia. It has fused sepals and petals, which is a very uncommon character in the basal eudicots. Image from wikipedia.org

A few species of the recently disbanded genus Corydalis grow in Ireland, including Ceratocapnos claviculata and Pseudofumaria lutea. They are also in the sub-family Fumaroideae and have irregular flower shapes.

Pseudofumaria lutea often seen in gardens, but is naturalised to old walls nearby. Image from wikipedia.org

Next blog post will be continuing on with the basals, but focusing on Ranunculaceae, the Buttercup family