Tick-trefoils
What are they?
The Tick-trefoils are members of the Pea Family and most species have thin, woody stems. Some are trailing, others form low, twiggy bushes, up to three feet high. These plants get their English name from the seed pods, which have hooked hairs on them (like velcro!) which are designed to hook onto animal fur as a dispursal mechanism - just like the legs of ticks.
Where are they found?
These are mostly plants of open fields and woodland margins, hedgerows and roadsides.
Identification
Identification of some species can be tricky and should be based on close examination of stem and leaf hairs. The shape and details of the seed pods can also be useful.
Trailing Tick-trefoil Desmodium glabellum
Found in sandy places along woodland margins and other shady places. Flowers June to September.
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Hoary Tick-trefoil Desmodium canescens
Typically found along woodland margins and other shady places. Cape May has an isolated population, suggesting that it may be introduced in our area. Flowers July to September.
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Panicled Tick-trefoil Desmodium paniculatum
Not uncommon in dry fields, woodland margins and other grassy places. Flowers July to September. Leaves variable, but always with a fairly long petiole and each leaflet much longer than wide. Stems smooth.
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Velvet-leaved Tick-trefoil Desmodium viridiflorum
Uncommon in dry woodland. Flowers July to September.
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Rigid Tick-trefoil Desmodium obtusum
Uncommon in dry, sandy fields and woodland edge. Flowers August to September. Leaves small, with side leaflets that are longer than the petiole (compare with Maryland Tick-trefoil).
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Maryland Tick-trefoil Desmodium marilandicum
Uncommon in dry, sandy fields and woodland edge. Flowers August to September. Closely resembles Rigid Tick-trefoil but leaf petioles are longer.
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Small-leaved Tick-trefoil Desmodium ciliare
Uncommon in dry, sandy fields and coastal dunes. Flowers July to September. Trails low to the ground so easily overlooked in rank grass unless in flower.
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Naked-flowered Tick-trefoil Hylodesmum nudiflorum
Uncommon along roadsides and trails in rich woodland soils. Flowers late July to September.
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