Ornamentals and Edibles: the Rosaceae, part two

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apple blossom (Malus domestica), unknown cultivar growing wild

Gardeners grow many rose family plants beyond roses themselves. Herbaceous ornamentals and shrubs include lady’s mantle (Alchemilla), goat’s beard (Aruncus), meadowsweet (Filipendula), avens (Geum), burnet (Sanguisorba), false spiraea (Sorbaria), cinquefoil (Potentilla), kerria, spiraea, flowering quince (Chaenomeles), pyracantha, and cotoneaster. Trees include hawthorn (Crataegus), mountain ash (Sorbus), ninebark (Physocarpus), and of course the flowering plums and cherries.

Unfortunately a few of these species are considered invasive: multiflora rose (Rosa multiflora) and wineberry (Rubus phoenicolasius) are two especially bad ones in the mid-Atlantic. And then there’s the horribly prolific Bradford pear, a cultivar of Pyrus calleryana that was selected at the USDA Plant Introduction Station in Glenn Dale, Maryland, at one time a very popular street and landscaping tree. You can find them all over the place now, in quasi-wild situations like in the median of Interstate 95 north of the Washington Beltway. Ever notice all the beautiful white blooming trees there in early spring? Bradford pear.

Despite the prevalence of rosaceous plants in the nursery industry, the major economic importance of the family is from foodstuffs. Here’s a partial list of edibles in the Rosaceae:

  • Amelanchier species   serviceberry
  • Cydonia oblonga   quince
  • Eriobotrya japonica   loquat
  • Fragaria species (at least 20, plus hybrids)   strawberry
  • Malus domestica   apple
  • Mespilus germanica   medlar
  • Prunus armeniaca   apricot
  • Prunus dulcis   almond
  • Prunus persica   nectarine, peach
  • Prunus species (several)   cherry
  • Prunus species (several)  plum
  • Pyrus communis   pear
  • Rubus caesius (and about a dozen others)   dewberry
  • Rubus chamaemorus   cloudberry
  • Rubus idaeus, R. strigosus, and others   red raspberry
  • Rubus x loganobaccus*   loganberry
  • Rubus occidentalis   black raspberry
  • Rubus ursinus (and others) blackberry

Boysenberry was developed from R. idaeus, R. fruticosus, R. aboriginum, and R. x loganobaccus.*

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Pyrus species (I think)

The above list gives an idea of how complicated the taxonomy of this family must be. Malus domestica is actually a catch-all name, since the genetic history of domesticated apples is incredibly complex. It’s believed that the progenitor of our more than seven thousand known cultivars of apple is M. sieversii, native to western Asia.

Rose family plants form several different types of fruits. The various Prunus species bear drupes (colloquially, stone fruits), which consist of a skin enclosing a fleshy layer of tissue, which surrounds a hard pit or stone, which encloses the seed. Although we call them berries, the fruits of the Rubus species are also drupes, or more specifically they are aggregates of drupelets (a drupelet being nothing more than a small drupe).

Apple, pear, serviceberry, loquat, quince, and medlar produce pomes, a type of fruit in which a skin and fleshy layer enclose a layer of cartilage, which encloses several seeds.

And then there’s accessory fruits, in which tissue not derived from an ovary supports the actual fruits. In the case of Fragaria species the fruits are achenes (dry, hard fruits that don’t split open at maturity). So those annoying “seeds” of strawberries are the real fruits. The fleshy part forms from the enlarged area at the top of the flower stalk.

None of the fruits of rosaceous plants are true berries. In the botanical sense, a berry is an indehiscent fruit (meaning it doesn’t split open at maturity) that consists of a fleshy layer surrounding several or many seeds, and the seeds are not surrounded by a hard shell. So if the rosaceous “berries” are not actually berries, what are? Tomatoes. Grapes. Passionfruit. Bananas. Blueberries.

prunus persica?

Prunus species, possibly P. persica

A few of the rosaceous fruits listed above are native to North America: some of the Amelanchier, Rubus, and Fragaria species. Most of the cultivated Prunus species are Eurasian in origin, though there are some edible plums native to the new world.

next time: the wildflowers

*the lowercase “x” in a botanical name denotes an interspecific (between species) cross

Plants Be Complicated: the Rosaceae, part one

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serviceberry (Amelanchier species)

When writing about plant families, I like to quote a few statistics, but that isn’t so easy with the Rosaceae. A web search of “number of species in Rosaceae” yields the following:

 

 

 

  • “…4,828 known species in 91 genera” (Wikipedia)
  • “…9,404 scientific plant names of species rank for the family Rosaceae. Of these 1,966 are accepted species names….[there are] a further 2,836 scientific plant names of infraspecific rank…” (The Plant List)
  • “…some 2,500 species in more than 90 genera.” (Britannica.com)
  • “Worldwide, there are about 100 genera and 3,000 species.” (Wildflowers and Weeds)
  • “The Rosaceae comprises approximately 3,400 species…” (USU Herbarium)
  • “…comprising about 100 genera and 3,000 species.” (University of Hawaii)

You get the idea. But why is it so hard to pin down? For one thing, people are still discovering previously undocumented plants. More significantly, studies of genetics and evolutionary history change our understanding of how organisms are related to one another, leading to changes in how they’re classified. Sometimes several species are lumped into one; other times, one species is split into several, leading to the creation of new species.*

When it comes to the Rosaceae, there’s another factor: apomixis. Simply put, this is the ability of a flowering plant to reproduce via seed that has formed asexually. Which sounds wrong, because we all know that seeds are formed when ovules are fertilized by pollen…right?

But then, as a botanist friend put it, “plants be complicated.”

There are several mechanisms by which apomixis occur, and a summary is beyond the scope of this blog (that is, I don’t fully understand it yet myself), but the upshot here is that apomixis kinda-sorta might result in the formation of new species; at the least, it muddies our ability to trace genetic relationships:

Apomixis also frequently leads to the formation and maintenance of numerous morphologically distinct, yet interfertile, varieties growing true to type from seed. The taxonomy of such agamic complexes can be a difficult and contentious task…   –Understanding Apomixis: Recent Advances and Remaining Conundrums
Ross A. Bicknella and Anna M. Koltunowb
(full article)

According to the Wikipedia entry, the genus Cotoneaster contains between 70 and 300 species, Crataegus between 200 and 1,000, and Rubus may have thousands.

It seems futile, then, to say how many species are in the Rosaceae, but I’ll continue with a few more statistics. According to BONAP, the Rosaceae is the fifth largest family in North America (counting natives only), with 664 species. The Maryland Biodiversity Project has records for 142 species, about half of which can be found in the piedmont. About 40 of the Maryland species are aliens, eight are listed S1, three are S2, and five are S3.

Species in the Roscaeae occur worldwide except the arctic and antarctic, with the greatest diversity found in the northern hemisphere. The flowers almost always consist of five sepals, 5 petals, and many stamens (ten or more), all fused together at their base into a cup-shaped structure termed a hypanthium. The flowers are borne in racemes, spikes, or heads, or sometimes singly. Leaves are usually arranged alternately on the stem, can be simple or pinnately compound, usually have stipules, and often have toothed margins. Herbaceous plants are usually perennials, and woody plants are usually deciduous.

This is a family of major economic importance, and not just for cut roses in the flower industry. More on that next time.


*interesting article: Whence Lumpers and Splitters? (National Center for Science Education)

More Anguillan Wildflowers

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Heliotropium currassavicum (Boraginaceae)
An herbaceous pantropical with the common names small seaside lavender, wild lavender, and salt heliotrope, it’s also found in much of the United States and even in Canada. Looks a lot like the Cryptanthas that were making me crazy last spring.

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Borrichia arborescens (Asteraceae)
A low-growing shrub of rocky coastlines throughout the Carbbean, this species has the common names seaside tansy, lavender, and drug-a-man.

 

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Erithalis fruticosa (Rubiaceae)
Black torch (or candlewood, or jack lantern) is a shurb native to Florida (where it’s threatened), Central America, Venezuela, and some of the Caribbean.

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Sida ciliaris (Malvaceae) Common names include bracted fanpetals and twelve o’clock weed. It’s a perennial herb native to the tropical and subtropical Americas. Taxonomic trivia: according to Wikipedia, Sida is a “wastebasket” taxon, meaning it’s a place to put species that don’t fit into any other genera.

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Strumpfia maritima (Rubiaceae) Another Caribbean native, this coastal shrub has several common names, including rosemary, pride of Big Pine, candle torch, mosquito bush, rosemarin bord de mer, and womaren bolanme.

 

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Suriana maritima (Surianaceae) Baycedar is a pantropical shrub of coastal habitats. It flowers year round.

 

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Tecoma stans (Bignoniaceae) Known as trumpetflower, yellow trumpetbush, yellow bells, yellow elder, and ginger-thomas in a shrub or small tree native to Central and South America

 

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Wedelia species (Asteraceae) Wedelia is a large genus with over one hundred species, some of which have been re-assigned to other genera; many are commonly called creeping ox-eye. There simply isn’t enough information on the internet for me to say for sure which one this is. My initial tentative conclusion was W. calycina, but that name may no longer be accepted. Sometimes I just have to say “good enough” and move on. DYCs.

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Anguilla

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Anguilla, northern-most of the lesser Antilles in the Caribbean, is an eel-shaped island about 16 miles long and three miles wide, consisting mostly of a two hundred foot thick layer of limestone over an igneous base. There’s not much elevation change (highest point is about 210 feet above sea level), no springs or streams, and only a little fertile soil. The resulting vegetation is what you’d expect: low-growing, scrubby stuff adapted to harsh conditions.

Maybe 120 of the almost 500 plant species found on Anguilla are thought to be alien, but reports vary. One source theorizes that aliens have had a difficult time establishing on Anguilla because there were never any large plantations offering more hospitable starting places.

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Steve and I were there for four days in mid-January. There aren’t any hiking trails as such, but we walked to some uninhabited areas anyway. I brought an older camera and did a lot of point-and-shoot photography, and have identified about 24 species of flowering plants, because even though we were supposed to be relaxing, I can’t resist botanizing in a new place.

The pea and morning glory families were well represented.

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Canavalia rosea (Fabaceae)
Now that’s a papilionaceous flower if ever I saw one. This vine is found in tropical regions worldwide and goes by the names bay bean, beach bean, cow bean, sea bean, vonvon, and who knows how many others.

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Centrosema virginianum (Fabaceae)
This one has many common names, among them blue bell also known as wild pea, pwa pwa, butterfly pea, and winer. It’s native to tropical and subtropical regions of South and North America, including Maryland (in the coastal plain). When I spotted it I was immediately reminded of Atlantic pigeonwings (Clitoria mariana.)

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Desmanthus virgatus (Fabaceae)
A short shrub native to tropical and subtropical regions of the Americas, with a million common names, among them wild tantan and dwarf koa.

 

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Stylosanthes hamata (Fabaceae) Cheesytoes is native to tropical and subtropical North America. I found it growing as a lawn weed and as such, the plants were very compact and short, but it can get to about two feet tall, and is apparently an important forage species. There are at least two dozen other names for this species, including Caribbean stylo, lady’s fingers, sweet weed, and wild clover.

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Merremia dissecta (Convolvulaceae)  Cut-leaf morning glory is a native of the Americas, now established in tropical and subtropical regions worldwide. Other common names include noyau vine, bini bini, nora vine, saba spice bush, and alamo vine. I found in growing inland, not right along the beach like so many of these plants.

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Ipomoea eggersii (Convolvulaceae) “Almost endemic” according to the Plants of the Eastern Caribbean website, jumby potato is a vine of coastal forests and scrubs, found in the Lesser Antilles, Virgin Islands, and a few other Caribbean islands.

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Ipomoea pes-caprae (Convolvulaceae) This fast-growing vine can reach lengths of thirty feet and can be found in tropical and subtropical beach areas worldwide. It’s considered a noxious weed in Arkansas and Arizona. Common names include beach morning glory, railroad vine, bayhops, and goat’s foot.

 

sources
Plants of the Eastern Caribbean
Anguilla Environmental Profile
Geology and Botany of Anguilla

next time: more Anguillan wildflowers