Woodland Pinedrops (Pterospora andromedea) ... Carnivorous?

Woodland Pinedrops

Pterospora andromedea

Location: Bandon State Natural Area (BSNA)

Bandon, Oregon

Glandular hairs exude a sticky substance to which small insects adhere.

Primary Inquiry

Do Woodland Pinedrops secrete enzymes that digest insect protein
and incorporate amino acids in their tissue to capture nitrogen?

Is the Woodland Pinedrop carnivorous ... "protocarnivorous"?

by: Keith Franklin Saylor

This plant is the tallest I've observed in BSNA,
measuring almost 90cm (around 3 feet).

Woodland Pinedrops Photo Essay Click on Images to View Larger Photos.

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Fig. 1. In BSNA, Pinedrops are observed generally in open shorepine stands that have the look and feel of a conifer savannah natural feature.	Fig. 2. Pinedrops on the mound beneath shorepine trees.
Fig. 3. Pinedrops corolla flower.	Fig. 4. Pinedrops fruit.
Fig. 5. Pinedrops in situ	Fig. 6. Pinedrops in situ.
Fig. 7. The stalk contains glandular hairs that exude a sticky substance.	Fig. 8. Insects are trapped in the glandular hairs.
Fig. 9. Muliple insects trapped on stem.	Fig. 10.
Fig. 11. Up to 20 insects were counted trapped on one plant with some plants showing 3 or 4.	Fig. 12.
Fig. 13. Insects measured are between 2mm and 5mm.	Fig. 14. Close-up of insect in fig.13.
Fig. 15.	Fig. 16.
Fig. 17. The leaves of the plant also have glandular hairs.	Fig. 18. This insect may be Chilenocaecilius ornatipennis an species not native to the United States.
Fig. 19. The tubular corolla petals have little to no glandual hairs that secrete an adhesive substance; while both are present on the outer margins of the calyx sepals.	Fig. 20. The fruit do not show glandular hairs. However the marginal glandular hairs are present on the calyx. This image shows the petals of the corolla peeling away from the developing fruit.

I have failed finding any scientific documentation showing Pinedrops secrete enzymes that breakdown insect tissue to capture nitrogen (See Inquiry). That is, that they are carnivorous or "protocarnivorous". I have found a discussion in Mountain Wildflowers of the Southern Rockies: Revealing their Natural History by Dunmire and Dobson page 45 which reads: "Pinedrops and other protocarnivorous species have an advantage over other plants in situations where soil nitrogen is scarce. These plants immobilize insects and other small herbivores by trapping them in sticky stem glands and then release enzymes that digest the animal protein and incorporate the amino acids in their tissues. A trapped insect quickly stimulates enzyme secretion, capturing the nitrogen before insectivores steal the prey." This quotation from Dunmire and Dobson is not supported by research or experimental documentation. I wonder whether the writers may be of the opinion that, because other plant species are shown to breakdown insect tissue through substance exuded by glandular hairs, Pinedrops is the same. It is a fair assumption which may be drawn from compelling observational evidence. If anyone is aware of documentation based upon lab based scientific experimentation of whether Pinedrops are carnivorous or protocarnivorous, please comment below with the reference. I will update this document as I find (or made aware of) any documentation. Keith Franklin Saylor kfsaylor@gmail.com

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© by Keith F. Saylor 2025

First Published August 2025