Jake Dalzell

by Jake Dalzell, Hazel Garrett, Catriona Forrest, Wayne Liang, Rosalind Mackey, Denis Pavlov, and Josh Simpson  This was a small project we threw together over three days on our Plant Sciences fieldtrip to Portugal. Everyone on the fieldtrip used six different techniques to explore plant physiology and ecology, and each group came up with a research question that could be answered using some of these techniques.

Comparing parasite and host strategies in a Portuguese grassland

7/10/2023 UPDATE: I have discovered other authors came up with this idea before me, as noted by Press and Phoenix¹¹. At least two authors have mentioned it: in the context of mistletoes¹²; and a North American root hemiparasite,

 Triphysaria

¹³. However, as far as I can tell the hypothesis has never been tested.

Total ecosystem evapotranspiration – an overlooked factor in grassland hemiparasite ecology?

In July I spent a few days in Sligo as a field assistant with an international, interdisciplinary team who are studying peritidal stromatolites. Stromatolites are layered rock formations created by microbes, and peritidal stromatolites form in the area of the shore that is affected by seawater from the tide or from sea spray. This makes them unique as they can experience large changes in salinity.

Sligo Stromatolites

This summer I am cataloguing the flora and plant communities of twelve islands [EDIT 20/11/22: it ended up being eleven islands!] in Strangford Lough, with the help of a BSBI Plant Study Grant. The goal is to have a complete species list of each island and a map showing all of the plant communities and where they occur. I have been kayaking to these islands and doing a thorough survey, and also quadrats in each distinct plant community.

The Islands Project

Since 2022 I have been recording the flora of some islands in Strangford Lough. I received a Plant Study Grant from the BSBI to work on this in the Summer of 2022 but as it turned out I had committed to a much bigger project than I first thought! I recently submitted my records and can now finally say I have finished my first large recording project.

Strangford Lough flora: an update

This is an adapted version of my poster, which is also available as a pdf or png. As with all my work on this site it is CC BY 4.0 (free for use/adaptation as long as I am credited).

The Meadow Maker Yellow Rattle (

 Rhinanthus minor

) has become well known in restoration ecology and wildlife gardening as a “meadow maker”, which can transform a species-poor patch of grasses into a biodiverse and flower-rich one.

Yellow Rattle

The model in this post is based on the one in Cameron et al. (2009), improving how seed dispersal is modelled and the dynamics are visualised.

I have become a bit obsessed with hemiparasitic plants recently. When I found Cameron et al.’s paper on how Yellow Rattle can create interesting spatial dynamics in grasslands¹, I got quite excited. I have been learning python this year so I thought I may as well try to replicate their model.

Modelling Yellow Rattle in a simulated grassland

My favourite butterfly, which I first saw during lockdown. They are the most delicate of the white species (Pieridae) found in Ireland and flutter through grasslands in May and June. Taxonomy For a long time, scientists wondered why Wood Whites (

 Leptidea sinapis

) were fairly widespread and common in Ireland, when they were so rare in England.

The Cryptic Wood White butterfly

As someone who has been deeply interested by plants as long as I can remember, I have grown to appreciate all the different habitats I come across in Ireland. Each has its own unique set of species, but one that has always particularly caught my attention is our grasslands.

Why care about grasslands?

Today I had the opportunity to work as a field assistant with a PhD student, Thomas Marquand. He is researching CO₂ and methane dynamics in soil in restored and reclaimed fens in East Anglia (with the Centre for Landscape Regeneration). We took samples from the fen exhibit in the Cambridge Botanic Gardens and used a spectrometer to measure CO₂ and methane concentration, and also δ¹³C-CO₂.

Fen soil carbon flux

Today I went to the BSBI’s November conference in the Natural History Museum in London! I presented my poster on my summer project surveying islands on Strangford Lough, and got to do a 60 second flash talk. It was really great to meet other people who are passionate about plants and learn from them. Read the html version of my poster here. Watch my (very brief!) flash talk here.

British and Irish Botanical Conference, November 22

03/11/2023 EDIT:

actually a rediscovery, this species was recorded in Belfast pre-1930 Earlier this year, I found a species of grass I didn’t recognise, growing as a pavement plant in East Belfast. With a guide I identified it as

 Polypogon monspeliensis

(Annual Beard-grass), a new species for County Down. This species is known from Dublin and Cork, and there is a previous Ulster record from Keady in Armagh.

Annual Beard-grass: a new species for County Down (H38)

Ants visit a Sea Campion flower infected by a

 Microbotryum

smut fungus. Disease is something few people love. There are exceptions though, particularly among those who appreciate the diversity and ecological role of plant disease.

In Defence of Disease

Hemiparasitic plants are those which steal water and nutrients from other plants, but still photosynthesise (so are green). They are an interesting part of the Irish flora, and some can play an important role in grasslands by weakening other plants – particularly Yellow Rattle.

Hemiparasitic plants in Irish grasslands

Slievenacloy Nature Reserve is an Ulster Wildlife reserve in Antrim. It is very well managed for upland grassland, with a wealth of Devil’s-Bit dominated grassland.

Plasmopara euphrasiae: a downy mildew species new to Ireland

On the thirteenth of August, I was at Killard National Nature Reserve, Co. Down, with my mum. We were looking for Frog Orchids and other species rare in the county like Quaking Grass and Field Scabious. She found a plant she didn’t recognise and asked me what it was, and it was Autumn Lady’s Tresses. I knew I hadn’t seen it before and wasn’t sure it had been recorded anywhere near before.

Autumn Lady’s Tresses: an orchid species new to Ulster

In the nineties, the Belfast Naturalists’ Field Club extensively surveyed the urban flora of Belfast, resulting in a book,

 Urban Flora of Belfast

. Many plants new to Down and Antrim were found, and most of these were new to Ireland as well. This was a three-year effort involving some thirty-one recorders.

Belfast’s urban flora

Irish Plants

by Jake Dalzell, Hazel Garrett, Catriona Forrest, Wayne Liang, Rosalind
Mackey, Denis Pavlov, and Josh Simpson

This was a small project we threw together over three days on our Plant
Sciences fieldtrip to Portugal. Everyone on the fieldtrip used six
different techniques to explore plant physiology and ecology, and each
group came up with a research question that could be answered using some
of these techniques. Given the short time frame, our samples were biased
and small (too small for robust statistics!). We can't really draw any
hard conclusions from our results, but they do show interesting trends.

Our project compared the strategies used by two parasitic plants in the
Orobanchaceae and a shared host species in the Fabaceae. We also
compared host individuals which were parasitised by each species with
each other and with uninfected hosts. We were particularly interested in
how water use differed between the different plants. We expected to see
a lower water potential in the parasites than in their host, as has been
shown in other Orobanchaceae︎¹^,^². This water potential gradient
generates a sink, so there is a flux of xylem fluid from host roots to
parasite¹.

### Study species {#study-species .wp-block-heading}

We chose to study a holoparasite, *Phelipanche ramosa*; a hemiparasite,
*Bellardia trixago*; and a legume that they both parasitise, *Medicago
polymorpha*. These were abundant in the grassland where we were staying,
Quinta de São Pedro.

::: {.wp-block-group .is-nowrap .is-layout-flex .wp-container-core-group-layout-1 .wp-block-group-is-layout-flex}
<figure class="wp-block-image size-medium">
<img
src="https://irishplants.org/blog/wp-content/uploads/2023/03/phelipanche-225x300.jpg"
class="wp-image-414" loading="lazy" decoding="async"
srcset="https://irishplants.org/blog/wp-content/uploads/2023/03/phelipanche-225x300.jpg 225w, https://irishplants.org/blog/wp-content/uploads/2023/03/phelipanche-768x1024.jpg 768w, https://irishplants.org/blog/wp-content/uploads/2023/03/phelipanche-1152x1536.jpg 1152w, https://irishplants.org/blog/wp-content/uploads/2023/03/phelipanche-1536x2048.jpg 1536w, https://irishplants.org/blog/wp-content/uploads/2023/03/phelipanche.jpg 1619w"
sizes="(max-width: 225px) 100vw, 225px" width="225" height="300" />
<figcaption>Phelipanche ramosa</figcaption>
</figure>

<figure class="wp-block-image size-medium">
<img
src="https://irishplants.org/blog/wp-content/uploads/2023/03/bellardia-225x300.jpg"
class="wp-image-415" loading="lazy" decoding="async"
srcset="https://irishplants.org/blog/wp-content/uploads/2023/03/bellardia-225x300.jpg 225w, https://irishplants.org/blog/wp-content/uploads/2023/03/bellardia-768x1023.jpg 768w, https://irishplants.org/blog/wp-content/uploads/2023/03/bellardia.jpg 1069w"
sizes="(max-width: 225px) 100vw, 225px" width="225" height="300" />
<figcaption>Bellardia trixago</figcaption>
</figure>

<figure class="wp-block-image size-medium">
<img
src="https://irishplants.org/blog/wp-content/uploads/2023/03/medicago-225x300.jpg"
class="wp-image-416" loading="lazy" decoding="async"
srcset="https://irishplants.org/blog/wp-content/uploads/2023/03/medicago-225x300.jpg 225w, https://irishplants.org/blog/wp-content/uploads/2023/03/medicago-768x1024.jpg 768w, https://irishplants.org/blog/wp-content/uploads/2023/03/medicago.jpg 1013w"
sizes="(max-width: 225px) 100vw, 225px" width="225" height="300" />
<figcaption>Medicago polymorpha</figcaption>
</figure>
:::

<figure class="wp-block-image aligncenter size-full is-resized">
<img
src="https://irishplants.org/blog/wp-content/uploads/2023/03/haustoria.jpg"
class="wp-image-422" loading="lazy" decoding="async"
srcset="https://irishplants.org/blog/wp-content/uploads/2023/03/haustoria.jpg 1080w, https://irishplants.org/blog/wp-content/uploads/2023/03/haustoria-232x300.jpg 232w, https://irishplants.org/blog/wp-content/uploads/2023/03/haustoria-768x993.jpg 768w"
sizes="(max-width: 270px) 100vw, 270px" width="270" height="349" />
<figcaption>root connections are visible between the
Phelipanche and a host Fabaceae sp.</figcaption>
</figure>

### Mycorrhizal staining {#mycorrhizal-staining .wp-block-heading}

We cleared the roots using Sodium hydroxide, then stained for
mycorrhizal fungi by using a blue dye that binds to chitin, followed by
washing with Hydrochloric acid and then water.

::: {.wp-block-group .alignfull .is-content-justification-center .is-nowrap .is-layout-flex .wp-container-core-group-layout-2 .wp-block-group-is-layout-flex}
<figure class="wp-block-image size-medium">
<img
src="https://irishplants.org/blog/wp-content/uploads/2023/03/washingRoots-225x300.jpg"
class="wp-image-412" loading="lazy" decoding="async"
srcset="https://irishplants.org/blog/wp-content/uploads/2023/03/washingRoots-225x300.jpg 225w, https://irishplants.org/blog/wp-content/uploads/2023/03/washingRoots-768x1024.jpg 768w, https://irishplants.org/blog/wp-content/uploads/2023/03/washingRoots-1152x1536.jpg 1152w, https://irishplants.org/blog/wp-content/uploads/2023/03/washingRoots.jpg 1536w"
sizes="(max-width: 225px) 100vw, 225px" width="225" height="300" />
<figcaption>Josh and Catriona washing roots</figcaption>
</figure>

<figure class="wp-block-image size-medium">
<img
src="https://irishplants.org/blog/wp-content/uploads/2023/03/mycorrhizalStain-300x225.jpg"
class="wp-image-413" loading="lazy" decoding="async"
srcset="https://irishplants.org/blog/wp-content/uploads/2023/03/mycorrhizalStain-300x225.jpg 300w, https://irishplants.org/blog/wp-content/uploads/2023/03/mycorrhizalStain-768x576.jpg 768w, https://irishplants.org/blog/wp-content/uploads/2023/03/mycorrhizalStain-1536x1152.jpg 1536w, https://irishplants.org/blog/wp-content/uploads/2023/03/mycorrhizalStain.jpg 2048w"
sizes="(max-width: 300px) 100vw, 300px" width="300" height="225" />
<figcaption>Wayne, Jake, and Rosalind staining mycorrhiza</figcaption>
</figure>
:::

The results were fairly clear: the parasites had minimal fungal
infection (holoparasite) or none (hemiparasite), while the host had many
hyphae and arbuscules. The hyphae visible in the holoparasite may have
been an early stage of mycorrhization but the way the samples were
prepared means the context of the root was lost. Fungal structures are
visible in blue:

::: {.wp-block-group .is-content-justification-center .is-nowrap .is-layout-flex .wp-container-core-group-layout-3 .wp-block-group-is-layout-flex}
<figure class="wp-block-image size-medium">
<img
src="https://irishplants.org/blog/wp-content/uploads/2023/03/holoRoot-300x300.jpg"
class="wp-image-417" loading="lazy" decoding="async"
srcset="https://irishplants.org/blog/wp-content/uploads/2023/03/holoRoot-300x300.jpg 300w, https://irishplants.org/blog/wp-content/uploads/2023/03/holoRoot-150x150.jpg 150w, https://irishplants.org/blog/wp-content/uploads/2023/03/holoRoot-768x768.jpg 768w, https://irishplants.org/blog/wp-content/uploads/2023/03/holoRoot-1536x1536.jpg 1536w, https://irishplants.org/blog/wp-content/uploads/2023/03/holoRoot-2048x2048.jpg 2048w"
sizes="(max-width: 300px) 100vw, 300px" width="300" height="300" />
<figcaption>holoparasite root with some hyphae visible</figcaption>
</figure>

<figure class="wp-block-image size-medium">
<img
src="https://irishplants.org/blog/wp-content/uploads/2023/03/hemiRoot-300x300.jpg"
class="wp-image-418" loading="lazy" decoding="async"
srcset="https://irishplants.org/blog/wp-content/uploads/2023/03/hemiRoot-300x300.jpg 300w, https://irishplants.org/blog/wp-content/uploads/2023/03/hemiRoot-150x150.jpg 150w, https://irishplants.org/blog/wp-content/uploads/2023/03/hemiRoot-768x768.jpg 768w, https://irishplants.org/blog/wp-content/uploads/2023/03/hemiRoot-1536x1536.jpg 1536w, https://irishplants.org/blog/wp-content/uploads/2023/03/hemiRoot-2048x2048.jpg 2048w"
sizes="(max-width: 300px) 100vw, 300px" width="300" height="300" />
<figcaption>hemiparasite roots with no fungal structures
visible</figcaption>
</figure>

<figure class="wp-block-image size-medium">
<img
src="https://irishplants.org/blog/wp-content/uploads/2023/03/hostRoot-300x300.jpg"
class="wp-image-419" loading="lazy" decoding="async"
srcset="https://irishplants.org/blog/wp-content/uploads/2023/03/hostRoot-300x300.jpg 300w, https://irishplants.org/blog/wp-content/uploads/2023/03/hostRoot-150x150.jpg 150w, https://irishplants.org/blog/wp-content/uploads/2023/03/hostRoot-768x768.jpg 768w, https://irishplants.org/blog/wp-content/uploads/2023/03/hostRoot-1536x1536.jpg 1536w, https://irishplants.org/blog/wp-content/uploads/2023/03/hostRoot-2048x2048.jpg 2048w"
sizes="(max-width: 300px) 100vw, 300px" width="300" height="300" />
<figcaption>host root with many hyphae and arbuscules</figcaption>
</figure>
:::

<figure class="wp-block-table is-style-regular">
<table
class="has-base-background-color has-background has-fixed-layout">
<tbody>
<tr class="odd">
<td></td>
<td>Host</td>
<td>Holoparasite</td>
<td>Hemiparasite</td>
</tr>
<tr class="even">
<td>Hyphae?</td>
<td>Yes</td>
<td>Yes</td>
<td>No</td>
</tr>
<tr class="odd">
<td>Arbuscules?</td>
<td>Yes</td>
<td>No</td>
<td>No</td>
</tr>
</tbody>
</table>
</figure>

The lack of mycorrhizae in the parasites suggests that they do not need
fungi to acquire resources as they can just steal them (and hence the
carbon cost of mycorrhizae is not worth it). The resources are acquired
from mycorrhizae at a carbon cost by the host, and then promptly stolen
by the parasites. It would be interesting to compare with a hemiparasite
grown without a host -- does it now form mycorrhizae, as it cannot steal
resources from other plants?

### Water relations {#water-relations .wp-block-heading}

Licor was used to measure stomatal conductance and other metrics, and
estimate water use efficiency. A pressure bomb was used to measure
instantaneous water potential in stems cut around 3cm from the base. The
holoparasite could not be measured using licor as it does not have
substantial leaves.

<figure class="wp-block-image aligncenter size-full is-resized">
<img
src="https://irishplants.org/blog/wp-content/uploads/2023/03/waterPotential.png"
class="wp-image-423" decoding="async"
srcset="https://irishplants.org/blog/wp-content/uploads/2023/03/waterPotential.png 3750w, https://irishplants.org/blog/wp-content/uploads/2023/03/waterPotential-300x200.png 300w, https://irishplants.org/blog/wp-content/uploads/2023/03/waterPotential-768x512.png 768w, https://irishplants.org/blog/wp-content/uploads/2023/03/waterPotential-1536x1024.png 1536w, https://irishplants.org/blog/wp-content/uploads/2023/03/waterPotential-2048x1365.png 2048w"
sizes="(max-width: 3750px) 100vw, 3750px" width="650" />
</figure>

The shoot water potential was much lower in the hemiparasite than in the
host, as expected. The holoparasite had a very high water potential,
which was unexpected. This may have been due to issues in measurement,
as the texture of the stems made gauging the point at which water was
visible at the cut end difficult. It may be that the water potential in
the tubercle of the holoparasite was lower as in *Cistanche*², so it
could still act as a sink on the host plant. The extremely high water
potential is still strange though, and merits further research.

<figure class="wp-block-image aligncenter size-full is-resized">
<img
src="https://irishplants.org/blog/wp-content/uploads/2023/03/conductance.png"
class="wp-image-420" decoding="async"
srcset="https://irishplants.org/blog/wp-content/uploads/2023/03/conductance.png 3000w, https://irishplants.org/blog/wp-content/uploads/2023/03/conductance-300x250.png 300w, https://irishplants.org/blog/wp-content/uploads/2023/03/conductance-768x640.png 768w, https://irishplants.org/blog/wp-content/uploads/2023/03/conductance-1536x1280.png 1536w, https://irishplants.org/blog/wp-content/uploads/2023/03/conductance-2048x1707.png 2048w"
sizes="(max-width: 3000px) 100vw, 3000px" width="500" />
</figure>

Stomatal conductance was considerably higher in the hemiparasite than in
the host, providing a mechanism for its low water potential.

<figure class="wp-block-image aligncenter size-full is-resized">
<img
src="https://irishplants.org/blog/wp-content/uploads/2023/03/wue.png"
class="wp-image-424" decoding="async"
srcset="https://irishplants.org/blog/wp-content/uploads/2023/03/wue.png 3000w, https://irishplants.org/blog/wp-content/uploads/2023/03/wue-300x250.png 300w, https://irishplants.org/blog/wp-content/uploads/2023/03/wue-768x640.png 768w, https://irishplants.org/blog/wp-content/uploads/2023/03/wue-1536x1280.png 1536w, https://irishplants.org/blog/wp-content/uploads/2023/03/wue-2048x1707.png 2048w"
sizes="(max-width: 3000px) 100vw, 3000px" width="500" />
</figure>

The water use efficiency of the hemiparasite was much lower than that of
the host. This can be explained by its high conductance.

Overall the hemiparasite has a strong "spender" strategy, freely using
resources that it gains from its host and transpiring a lot of water to
pull a low water potential and get more host resources.

### References {#references .wp-block-heading}

1. Ackroyd, Robert D., and Jonathan D. Graves. 1997. 'The Regulation of
 the Water Potential Gradient in the Host and Parasite Relationship
 between *Sorghum bicolor* and *Striga hermonthica*'. *Annals of
 Botany* 80 (5): 649--56. <https://doi.org/10.1006/anbo.1997.0506>.
2. Fahmy, Gamal Mohammad. 2013. 'Ecophysiology of the Holoparasitic
 Angiosperm *Cistanche phelypaea* (Orobanchaceae) in a Coastal Salt
 Marsh'. *Turkish Journal of Botany* 37: 908--19.
 <https://doi.org/10.3906/bot-1210-48>.