You just KNOW that some plants are considered weeds. Their common names give them away. They sound awful. Giant hogweed (Heracleum mantegazzianum). Ripgut brome (Bromus diandrus). Devil's claw (Proboscidea lutea). Smellmelon (Cucumis melo). Itchgrass (Rottboellia cochinchinensis). Dog-strangling vine (Cyanthum rossicum).

Others...well, others seem more benign. Even sweet. For Valentine's day I present to you nine weedy plants with lovely names. Enjoy...

1. Tree-of-Heaven (Ailanthus altissima). How celestial (Sigh...). How divine (Sigh...). How invasive (sigh...wait, what?). Tree-of-heaven is a deciduous tree, native to China, in the Simaroubaceae. It has been used, extensively, as a street tree; in fact it is the subject of A Tree Grows in Brooklyn by Betty Smith. But it suckers. A lot. And it stinks. A lot. And it spreads, rapidly, by seeds (lots and lots of seeds!) and root-sprouts. Some people living in urban areas have renamed it 'Tree-of-Hell'.

Tree of Heaven - Ailanthus altissima

2. Baby's breath (Gysophila paniculata). Baby's breath?!?!? Baby's breath?!?!? That delicate plant in the Pink family that is beloved by florists? You would have to work REALLY hard to make up a sweeter sounding name for a pest! Like 'Fuzzy kitten herb' or 'Baby giraffe weed'. Or 'Mouse ear chickweed' (That last one is real...). But baby's breath has become invasive in certain habitats, like Sleeping Bear Dunes in Michigan, where it escaped from gardens. 

3. Amaranthus spp. The genus name is derived from two Greek words: amarantos (unfading) and anthos (flower). There it is. Unfading flower. A perfect metaphor for love, no? Well, I've got two words of my own for you: PALMER AMARANTH. Enough said. (To be fair, many Amaranths are used worldwide as food sources, either leaves or seeds...but my animosity isn't directed at them.)

Palmer amaranth - Amaranthus palmeri

4. Love-apple (Solanum capsicoides). Sounds delicious, right? If you are talking about a tomato (Lycopersicon lycopersicum), sure. If you are talking about red soda apple (a.k.a. devil's apple and cockroach berry), not so much. The fruits are toxic and have been/are being used in many countries for rodent and insect control.

5. Multiflora rose (Rosa multiflora). A 'rose with many flowers', how can that be bad? HA! The intentions were good when this species was being promoted in the 19th and 20th centuries (ornamental shrub, erosion control, living livestock fence, wild-life food source), but things have gone terribly wrong since then. This shrub forms dense stands that can displace native vegetation.

6. Love leaves (Arctium minus). It sounds like you could brew up a nice aphrodisiac from this species. Although parts of the plant are said to be edible, love leaves, better known as common or lesser burdock, is also listed as being toxic in many weed guides. However, burdock doesn't make this list because of its questionable medicinal or culinary virtues, but rather for its seed. The tiny hooks on the seeds of this plant were the inspiration for velcro. Try pulling them out of the fur of a long-haired dog...

7. Heart's ease (Polygonum persicaria). Better know as smartweed or ladysthumb. This weed can grow everywhere, it seems. Seriously. It is even found in Greenland.

8. Love vine (Convolvulus arvensis). Love may keep us together, but you don't want to be in a relationship with this plant, which is better known as field bindweed. This perennial species is listed as one of the most noxious weeds in the WORLD. It has roots that can grow to depths of >10', it reproduces by seed and rhizomes, infrequent tillage just makes it mad, and repeated applications of herbicides are needed to suppress it. This plant also goes by the name possession vine...and you're nobody's property.

Field Bindweed - Convolvulus arvensis

9. Bouquet-violet (Lythrum salicaria). People love getting flowers on Valentine's day, right? Maybe you shouldn't send this 'bouquet', though, which you probably know better as purple loosestrife. This plant was introduced, intentionally, to North America as an medicinal herb, but it has since escaped from our gardens and become naturalized. Large infestations can alter water flow in streams and rivers, reduce native plant species diversity and negatively impact macrofauna, such as amphibians and waterfowl, that rely on wetlands for food and shelter. 

This post was originally published on the UC Weed Science Blog in 2014

https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=12890