P00119Montbretia showed up here several years ago. Of course, it did not take long for it to get very established. It is too shady for bloom, but not shady enough to inhibit vegetative proliferation. Those nasty stolons get everywhere, and grow into corms. They are so aggressive that they exclude English ivy! Seriously, they are the only species we know that can crowd out English ivy!

Some consider Montbretia to be the the genus name. Some consider it to be a common name for the genus of Crocosmia, or for a particular intergeneric hybrid. What is now so aggressively naturalized here might be Crocosmia paniculata. I really do not know. The few rare and sporadic blooms look like what I am familiar with in other landscapes, with branched inflorescences.

Now, I am aware of how aggressive their stolons are, and that their stolons swell into corms when they get to where they are going. I also know the physiology of simple corms, and that new replacement corms develop on top of old deteriorating corms. They might extend a few more stolons in the process, or put out a litter of cormels off to the side, but their technique is limited.

Well, it should be.

The technique demonstrated by this picture is weird. It seems to show a series of corms from the last twelve years. That makes sense if one corm replaces a previous corm annually. Longer accumulations can be found in older colonies. However, montbretia infested this landscape less than a decade ago, and took a few more years to disperse where these corms were unearthed.

Furthermore, after a decade, the oldest corms should be rotten and decomposed. Except for the stunted four year old corm, those that developed in the last six years seem to be suspiciously fresh.

Cortaderia jubata

P90908It is known by a few different common names, including ‘Andean pampas grass’, ‘purple pampas grass’, and simply ‘pampas grass’. ‘Andean pampas grass’ sounds almost like an oxymoron, since the Andes Mountains are in a separate region to the west of the pampas region of Uruguay and eastern Argentina. ‘Purple pampas grass’ is even sillier, since it is devoid of any purple.

I know it simply as ‘papas grass’. That is just how I learned it. The problem with this common name is that it is the same common name of Cortaderia selloana and its cultivars, which is a distinct species that is, on rare occasion, planted intentionally in landscapes. Cortaderia jubata is one of the most aggressively invasive of exotic species on the West Coast, so is not planted.P90908+

Cortaderia selloana is safe to plant because it is ‘supposedly’ sterile, so can not naturalize. Technically though, it is not really sterile, but merely exclusively female, without male flower parts for pollination. It reproduces by apomixis, which is a fancy way of saying that it produces viable seed without pollination. No one has bothered to explain why that makes it any less invasive.

Cortaderia jubata reproduces by apomixis too, but makes much more of problem with it. It is very prolific with its unpollinated seed! To make matters worse, it will hybridize freely with Cortaderia selloana if it gets the chance. How does that even work?! Pollen is needed for that sort of hanky panky! Nonetheless, the hybrids are almost as aggressive as Cortadera jubata is!P90908++

I just don’t trust any of them. Cortaderia selloana cultivars can work well in large landscapes in urban areas, where they can not escape into the wild. For rural or suburban landscapes that are near wildlands, there are plenty of other less invasive options.P90908+++

Bad Picture Of Good Berries

B90803KHimalayan blackberry is to cane berries what blue gum is to eucalypti. It is what gives all cane berries a bad reputation, and is why so few of us want to grow them. Himalayan blackberry grows as an extremely vigorous weeds, extending sharply thorny canes over anything within reach. When the canes are removed, the tough roots are extremely difficult to remove and kill.

If ignored, the canes ‘leap’, which means that they develop roots where they arch back downward to touch the ground. From there, they grow into new plants that extend new canes in all directions, to start the process all over again. (‘Leaping’ is like ‘layering’, which involves the development of roots where stems ‘lay’ on the ground.) Their seed gets where their canes do not.

The thorns are ‘prickles’, which really is a technical term for sharply pointed distensions of bark or epidermis. They are more like stout prickles of rose canes than the more finely textured prickles of garden varieties of cane berries. They are rigid, extremely sharp, and curved inward to snag victims on their way out; so are seriously wicked and potentially dangerous to handle.

Harvesting berries from second year canes is not easy. Most are out of reach within bramble thickets. Because they ripen through a long season, they must be harvested repeatedly, as those that were unripe during a previous harvest finish. This is why there are black, red and green berries in the same picture. The berries are small and variable, with good years and bad years.

This happens to be a good year. The thorny truss of a few small berries in the picture may not look like much; but there are plenty of them. The berries are quite richly flavored too. Those who have the patience to collect them will get some good jam or jelly out of the deal.

Creeping Saint John’s Wort

90717This is not the dreaded aggressively invasive Saint John’s wort that has naturalized in other regions. Nonetheless, creeping Saint John’s wort, Hypericum calycinum, does precisely as the name implies. It creeps, and has naturalized to a less aggressive degree in many spots near the coast. Its vigor is an advantage to many landscapes, but might eventually displease adjacent neighbors.

Creeping Saint John’s wort is a somewhat rustic perennial ground cover that does not need much water once established. It naturalizes in coastal climates because it gets all the water it needs from annual rainfall there. Although evergreen, it looks best if mown as winter ends. It happens to be susceptible to rust, and mowing removes much of the old foliage the the fungus overwinters in.

One to two inch wide bright yellow flowers, with five petals and prominent stamens, start to bloom in June and continue into September. By that time, the paired leaves might be getting tired if not watered, or infested with rust, but should stay presentable until mowing at the end of winter. Crowded plants might get three feet high. Otherwise, growth does not get much more than a foot deep.

Six on Saturday: Serious Weeds


The humongous perennial pea that I showed off last week was relatively innocuous. These six are some of the more prolific weeds. Actually, except for the first two, these are some of the most aggressive and problematic weeds in this region. All are exotic, which means that they are not native. Some were imported intentionally. Some were more likely stowaways. All except for #2 were found right outside here. #2 was found closer to town.

1. Vetch was most likely imported intentionally as a cover crop, forage crop or both. Because I do not know which vetch this is, I do not know why it is here. This is neither of the two species of vetch that are native here. It is a polite and pretty weed that never seems to become much of problem. Consequently, not much is known about it, or how it affects the ecosystem. Most of us just let it do what it wants to because it improves the soil.P90622

2. Queen Anne’s lace might have been imported intentionally because the young roots, young leaves and flowers are edible. It is, after all, a wild version of carrot. However, the small roots mature quickly and become too tough to eat, and often develop bad flavor. Furthermore, it is avoided because it it too easily confused with the extremely toxic poison hemlock! It can be a companion plant for attracting pollinators, but is mostly ignored.P90622+

3. Saint John’s wort was imported intentionally as a ground cover for landscapes, and escaped into the wild where it competes aggressively with native plants. It is toxic to grazing animals, so must be removed from where it appears in pastureland. Unfortunately, its wiry but tough stolons are extremely difficult to eradicate. This species is unavailable here, not just because it is invasive, but because it is so susceptible to rust. It never looks good.P90622++

4. Broom is one of the nastiest. Some believe it to be Scottish broom (which we call ‘Scotch broom’). Some believe it to be Spanish. Actually, it is most likely French. It doesn’t matter. It is terribly prolific and aggressive, with seed that remain viable and continue to germinate for many years after parent plants get removed. It was imported intentionally just because it is so pretty in bloom. So many of the worst weeds arrived here like that.P90622+++

5. Himalayan blackberry, like Queen Anne’s lace, might have been imported intentionally because it produces something edible. It happens to makes decent blackberries. However, it is neither as reliable nor as productive as garden variety blackberries. Berries might be sparse and of inferior quality, and are very difficult to pick because the canes are so very wickedly thorny! Canes are extremely vigorous and aggressive, and difficult to kill!P90622++++

6. Thistle was likely a stowaway. There is no realistic reason to have imported it. Nothing eats it. It is too wickedly spiny to handle. It does not work as a cover crop, although it does try to cover as much area as it can get its prolific seed into. There are other thistles that are more invasive, but none that are as mean as this one is with those formidable spines! I do not know for certain what species this is, but it is not one of the native thistles.P90622+++++

This is the link for Six on Saturday, for anyone else who would like to participate:


60323Some of the biggest and nastiest weeds are thistles. The most common is annual sowthistle, which can get taller than four feet in just a few months. It is relatively easy to handle, since the bristly foliage and stems are somewhat soft, almost like coarse lettuce. Blessed milkthistle is much nastier, with sharp foliar spines that can penetrate boots! It can get more than five feet tall and broad!

Most thistles are biennials or perennials, with spiny lobed foliage. They produce low foliar rosettes during their first year, and then bolt and bloom on tall floral stalks during their second year. Biennials usually die after bloom, but sometimes regenerate from the roots later. Perennials are more likely to regenerate and bloom annually for several years. Some thistles get rather shrubby.

The roots of many types of thistle would not be too difficult to pull from well watered soil if only the spiny foliage were not so difficult to handle. Larger plants might be easier to pry out with a shovel. If foliage is merely cut off at the the surface of the soil, it will regenerate from the large tap roots left below. However, cutting down flower stalks before bloom interferes with seed dispersion.

Horridculture – Ivy League

P90306English ivy, Hedera helix, is probably the nastiest and most aggressively invasive exotic species that I work with. It climbs high into redwood trees and overwhelms understory plants (that live below the trees). It invades many of the landscapes, and worst of all, it climbs building where it ruins paint and causes rot. It grows faster than we can keep up with it.

English ivy is actually a nice ground cover plant for refined landscapes. I grew it at my home in town. Contrary to popular belief, it does not root into and parasitize the trees that it climbs. Actually, it rarely overwhelms and shades out large trees. It prefers to keep them alive for support, from which it disperses its seed. However, it does promote decay in the trunks that it climbs, particularly where it retains moisture at ground level. Native trees are not accustomed to that.

We try to remove as much English ivy at work as possible, which includes removing it from trees and buildings. So far, with a few exceptions of small bits of ivy that broke off high in the trees that it climbed, I have been able to remove all ivy from the trees and walls that I have worked on.

Others were not so fortunate. When quick and efficient removal of ivy from the bases of as many mature trees as possible is the priority, ivy is more often severed down low, and left to die on the trunks of the infested trees. It looks shabby to say the least, and takes many years to deteriorate and fall away. In the picture above, dead ivy that was severed within the past few years is already being replaced by new ivy, which will also need to be severed.

The same technique happens with ivy on buildings. It gets cut at the foundations, but left on the walls to shrivel and turn brown. The dead ivy in the picture below was reaching upstairs eaves when it was severed, and remains there a few years later.

What annoys me so much about this technique is that it does not take much extra effort or time to tug quite most of the lower ivy from trees and walls. For most situations, all ivy can be dislodged, although tiny aerial roots remain. It is much easier to dislodge while fresh than after it is dried and crispy.P90306+

Unplanned Green Roof

p90106The last green roof that I wrote about was planned, although not in a typical manner. It is still my favorite green roof. Otherwise, I am none too keen on the fad. Very few buildings benefit from green roofs, and green roofs really do take more work than conventional landscapes in the ground.

The sort of green roof pictured here was most certainly not planned. It could have been the result of a an uncleaned gutter. All sorts of weeds can grow in the damp debris that can wash off of roofs, particularly in damp and foggy coastal climates where moisture so often drips from the edges of roofs. This gutter is just a short distance from the beach in Santa Cruz. The willows in the San Lorenzo River are next door.

Knowing what I know about this particular type of willow, I would guess that the cleanliness of the gutter, or lack thereof, was not really the problem. These aggressive willows can germinate in the slightest bit of debris, even under a single leaf that did not get rinsed or blown away fast enough. Once germinated, their finely textured roots are experts at clinging to anything that might otherwise get rinsed away. If there is not enough debris and dirt for them to grow in, they simply collect their own. Now that it has started the process, it will continue to collect debris and expand its root system until it gets removed or ruins the gutter. It seems to have already collected enough debris to share with a few grassy weeds nearby. It is mostly dormant now, and might have defoliated in the rain since this pictures was taken a few days ago. However, if it stays, it will resume aggressive growth as winter ends.

Tree of Heaven

50923‘A Tree Grows In Brooklyn’ documents the resiliency and invasiveness of the common but typically undesirable tree of Heaven, Ailanthus altissima. Once a single female tree get established, the extremely prolific seeds get everywhere, including cracks in concrete. The resulting seedlings conquer wherever they are not dug out. If cut down, they just resprout from the roots.

Male trees smell horrible while blooming for about a month in spring or summer. They are pollinated by flies, so naturally smell like what flies like. The tiny yellowish or tan flowers hang on panicles that can be a foot and a half long. Female blooms are not as big, prolific or objectionably fragrant. However, stems, leaves and all other parts of both genders smell rotten when handled.

Tree of Heaven, which has earned the alternative names of ‘tree of Hell’, ‘stink tree’, ‘ghetto elm’ and ‘ghetto palm’, is no longer a tree that gets planted by choice. It is typically a tree that plants itself, and on rare occasion, happens to grow into a good situation. They should not be allowed to overwhelm more desirable trees, or get too close to concrete or other damageable features.

Young trees grow very fast to about forty feet tall. Older and slower trees do not get much taller, although sheltered trees can get twice as tall, with elegant gray bark. They do not live much more than fifty years. The big pinnately compound leaves are surprisingly pretty. On vigorous shoots, individual leaves can get as long as two and a half feet, with leaflets as long as six inches.


P80915K.JPGJust about everything in this picture is icky! This species of pampas grass, Cortaderia jubata, is one of the most aggressive and noxious of the invasive exotic specie that have naturalized here. It seems to be incarcerated behind the weathered cyclone fence with barbed wire on top. The big water tank is is a harshly stark background. The tired old Douglas firs and ponderosa pines to the left and right seem to be unhappy here. The small coast live oak that is at least trying to make a more cheerful appearance is only oppressed by the surroundings. Only the clear blue sky above lacks the ick factor.

What is not visible in the picture is that there is no other flora in the area. Most of the area is covered with a thick layer of gravel to prevent vegetation from getting established close to the water tank. Weeds that manage to grow get cut down regularly. Only the pampas grass survives the ravages of the weed eater. It has been allowed to stay only because it has not yet been perceived to be a problem. It will probably be removed eventually as well. It would have been much easier to remove before it got so big. Now that it is blooming, it is likely to sow seed for more of the same.

Whomever gets the grim task of removing the pampas grass must contend with the nasty ‘razor grass’ foliage. The very sharp and very finely serrated edges of each leaf cause the worst sort of paper cuts! Even if handled very carefully, the long strap leaves have a way of getting everywhere. Someone tugging the base of the foliage with gloves and long sleeves can lose an ear to just one of the many long leaves that whip around so aimlessly.

However, someone who is unfamiliar with the serious nastiness of pampas grass might see this picture very differently. The firs, pines and oaks are not so bad. The water tank is a neutral background to the subject matter. The weathered cyclone fence with barbed wire on top, . . . well, let’s just say, . . . it’s ‘abstract’. Anyway, to someone who does not know better, the fluffy floral plumes of pampas grass that toss so many seed that have the potential to grow into an indefinite supply of the same nastiness are actually quite pretty.P89015K+.JPG