Weed of the Week - Growing low

Here's a weed of the week (WOTW) that ranges from utterly insignificant to just small.  It grows in a low, spreading mat, seldom more than a centimeter tall, and is sometimes called the sandmat or prostrate spurge. Officially it has the totally appropriate name Euphorbia prostrata. It can grow, quickly, from cracks or seams in sidewalks, and it is very prolific making lots of seeds so this naturalized annual is sure to reappear next year.  While it can be pulled (do take care, the milky sap can be irritating) an herbicide treatment is perhaps the only way to keep this weed under control.  However you can at least admire how efficiently it covers space, and of course, the remarkable beauty of its flowering and fruiting display.  There are a couple of similar species, E. maculata and E. serpens, but generally these species have smooth stems and leaves while E. prostrata is hairy. Ever wonder why botanists often have a hand lens, which is their version of bling?  It's to see if plants like this are hairy or not.

Weed of the week - pokin' around

The late summer and fall is when people notice that a huge, attractive looking weed has invaded their yard/garden/alley.  You can hardly miss a plant with big green leaves that stands anywhere from 4 to 8 feet tall on a red stem that is 1-2 inches in diameter.  Also notable are quite handsome racemes of dark purple to black, glossy berries.  There are some ornamental varieties of some other species. This is Phytolacca americana, pokeweed or just poke.  Warning: ALL PARTS OF THIS PLANT ARE TOXIC - DO NOT CONSUME, and if you are a sensitive skin type person, avoid the sap.  This plant is a perennial so a mature plant is not killed by cutting off the stem; you must poison the big old white tap root. or dig it out. The young shoots have been gathered and boiled as greens made famous by the song "polk salad (sallet) Annie".  Changes of water are needed to detoxify the greens and its least toxic when young; it scares TPP too much to even try it, And what would be left anyways.  In this case the "salad" stands for sallet in the British/French (?) sense of cooked greens.  Birds and even some small mammals seem able to eat the fruits with no ill effects, so too many seedlings appear under our bald cypress, a favorite perching tree. Best to pull seedlings or chop them off before they get that tap root formed.  

 Here's a flowering inflorescence; the flowers are small with 5 sepals that are persistent.

 This is an older inflorescence showing a sequence of fruit development.  It happens pretty fast.

 This is a nearly mature infructescence showing the round, slightly flattened purple/black berries.  Kids could easily eat any berries this attractive.  Note that the sepals have turned bright pink; thus prolonging their attractiveness even after a berry is removed.

This shows the foliage, a rather simple leaf and the distinctive pink stems.  

Weed of the week - ragweed

Your eyes may have just started to water just looking at these images of giant ragweed. The plants can reach 7-8 feet tall easy and a local walking/bicycling trail goes through a virtual gully of them just now coming into bloom. There are so many flowers they'll leave a yellow dusting of haploid males (pollen) on the ground.  Woe be to any allergic people who hazard this gauntlet.  Both the common and giant ragweeds are easy enough to recognize, but they are usually ignored in the spring when they are more easily controlled by mowing them down or whacking them out, or by herbicide application in the spring or early summer.  Too late now.  The smaller common ragweed showed up in an older blog and you will notice the highly lobed leaves that Linnaeus thought resembled wormwood, thus Ambrosia artemisiifolia.  Notice that the giant ragweed has three lobed leaves Ambrosia trifida (shown above) and the flowers are not showy at all because it's wind pollinated, so the co-flowering goldenrod gets the blame for hayfever. The flowers shown are just prior to flowering.  How long can you hold your breath?  

Weed of the week - Indian (mock) strawberry

Since TPP has no shortage of weeds, the weed of the week shall continue.  This one also generates a lot of queries from people and sometimes calls from the poison control center.  The Indian or mock or false strawberry is a terrible lawn weed, although it is even worse in a strawberry patch.  This is Duchesnea indica (due-kez-knee-ah), indeed a member of the rose family.  It's come up before on this blog.  The physical similarity to the standard strawberry of commerce is quite striking especially it strewing (another story there) habit of spreading by runners (stolons) and plantlets. The leaves are trifoliate and have very similar toothed margins (but not quite the same).  The flower has usually has 5 yellow petals (oops the flower photographed has 6) instead of white or pinkish petals, and they are subtended by a whorl of 3-lobed bracts (opposite the petals) below the 5 sepals (alternate with the petals).  The red strawberry like fruits generate the poisonous queries. It isn't toxic, but the fruit also has no taste.  The dead giveaway though are the achenes (the true fruits); they are red in Indian strawberry; and yellow/tan/brown in true strawberry.
The plant has the potential to be quite invasive especially in lawns but fortunately it is quite susceptible to standard lawn weed herbicides.  Although TPP doesn't like spraying, or have a great dislike of lawn weeds, patches can be easily spot treated before becoming a big problem.  It can be weeded by hand with some difficulty because of the runners and plantlets. Believe it or else, but this plant was human dispersed from its SE Asian place of origin for ornamental purposes.  This is on TPP's never plant this plant list, but you do sometimes find it for sale.