Pinedrop

Classification

Kingdom: Plantae

Phylum: Magnoliophyta

Class: Magnoliopsida

Figure 1- Pinedrop in natural habitat on forest floor.

Introduction

Pterospora andromedea, commonly known as Pinedrops, is a parasitic plant of the Heath family. This plant relies on mycoheterotrophy, the plant nutrition tactic that a plant takes nutrients like carbon from ectomycorrhizal fungi[1]. Pinedrops take advantage of the mycoheterotrophic process by taking the nitrogen, carbon, and broken down soil nutrients from the fungi, stealing nutrients fromplant roots specifically pine trees. Pinedrops are easily identified by their red stalk with bell-shaped flowers that hang upside down. Stems in the eastern United States tend to reach a maximum height of 50cm, while some species on the west coast reach 100cm.[4]

Range & Habitat

Pinedrops are native to coniferous forests of North America, and commonly grow from the soil below pine trees. Populations can be found in the United States, Canada, and Mexico, though it is most commonly found in mountainous regions such as the Northern Appalachians or the Rockies. Pinedrop grows well in acidic, well-drained, nutrient-poor soils [3]. They also need coniferous forests with ectomycorrhizal growth, which they rely on for nutrients. Pinedrops are more likely to be found in older forests with less disturbance because these conditions promote the growth of the fungi systems they prey on. In the eastern United States, Pinedrops are most commonly found in white pine forests[4].

Mycoheterotrophy and Role in Soil Ecology

The mutualistic relationship between pines and ectomycorrhizal fungi allows Pinedrops to survive. Pine trees produce glucose through photosynthesis, which is transferred through plant roots to fungi. In exchange, the fungus provides nutrients the tree is not capable of retrieving on its own, like nitrogen. Ectomycorrhizal fungi can also make it easier for the tree to collect water [2]. Pinedrops are parasites and take advantage of this mutualism by parasitizing the fungi. It is only a nuisance to the tree because the glucose being used to grow the fungi is going into supplying Pinedrops with the nutrients they need. These specific relationships and circumstances make the Pinedrop uncommon. They can also be used as an indicator to tell if a forest is thriving and when there are changes from effects like climate change[5]. Species like this will only be found in forests with high biodiversity and specific conditions.

Refrences

[1]Mycoheterotrophy - an overview | ScienceDirect Topics. (n.d.). . https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/mycoheterotrophy.

[2]Mycorrhizal fungi / RHS. (n.d.). . https://www.rhs.org.uk/biodiversity/mycorrhizal-fungi.

[3]Woodland Pinedrops. (n.d.). . https://www.fs.usda.gov/wildflowers/plant-of-the-week/pterospora_andromedea.shtml.

[4]Hazard, C., E. A. Lilleskov, and T. R. Horton. 2012. Is rarity of pinedrops (Pterospora andromedea) in eastern North America linked to rarity of its unique fungal symbiont? Mycorrhiza 22:393–402. https://link.springer.com/article/10.1007/s00572-011-0414-y

[5]Grubisha, L. C., B. A. Nelson, N. J. Dowie, S. L. Miller, and M. R. Klooster. 2014. Characterization of microsatellite markers for pinedrops, Pterospora andromedea (Ericaceae), from Illumina MiSeq sequencing. Applications in Plant Sciences 2:1400072.https://bsapubs.onlinelibrary.wiley.com/doi/full/10.3732/apps.1400072