A new ginkgophyte!

Wow, a new ginkgophyte.  Of course most plant lovers know the Ginkgo, Ginkgo biloba, the only living species of gickgophyte.  For those of you who still don't know your plant fossils all that well, gymnosperms were much more diverse in days past, which makes the job of finding flowering plant ancestors all the more difficult.  But the Ginkgophytes were certainly more diverse and this fossil makes them even more diverse than before, not because it's brand new, but because the preservation is so good you get a much better sense of the plant itself.  Zip over to the In Defense of Plants blog for a look-see and say hi to Umaltolepis.

Cretaceous to present - in 4 lectures

Well, as usual when teaching plant diversity, you get to angiosperms just at the end of the semester, but only by moving through gymnosperms rather quickly.  Angiosperms are the last major plant group to appear in the fossil record, and that appearance is about 135 million years ago.  So let's see that's almost 45 million years a lecture. Wow!  Time to get moving; a lot can happen in this period of time.  Consider this, the extinction of the dinosaurs perhaps due to a major asteroid impact occurred 65 million years ago, the event that defined the end of the Cretaceous. The vast majority of mammal evolution has taken place since then. Think about this. Grasses hadn't evolved yet, some thing that was necessary before the large mammalian herbivores could evolve, something that turned little forest understory browsers into the horse you are familiar with today.  Some of the dinosaurs were pretty big browsers too, but their primary food was ferns, conifers, and cycads.  What a change!  And of course the very recent intimate interaction between humans and plants in the form of agriculture has produced some winners (maize, soybeans) and some losers (tallgrass prairie plants). 

Today's laboratory - Conifer identification

Oh, this is so much fun!  Most people, and my students are no exception, except for a couple of the horticulture students, commonly think several incorrect things about conifers.  1. All conifers are evergreen and that evergreen and conifer are synonyms.  2. All evergreen conifers are "pine" trees.  3. All evergreen conifers basically look alike.  4. "Furs" are Christmas trees and animal pelts.  So today TPP will endeavor to correct at least one of these misconceptions.  If you set your goals too high, you get disappointed.
In a few moments, once this cup of coffee and this blog are finished, TPP will grab his clippers and wander around our arboretum to obtain some nice specimens.  After you spend a few decades at this you get pretty good at it and you recognize most common genera by sight.  On one of our Botanical Geek Tours (locale Swathmore's campus arboretum) this one almost had TPP stumped, but then from somewhere, probably a mental process of elimination based on what it could not be, and this genus popped to the fore.  So here you go school kids.  Identify this conifer.
Unfortunately this genus doesn't grow here in the upper midwest, so my ID key to common conifers (including one  uncommon genus, which is in my garden so what the heck) won't be any help.  Don't say TPP has never given you anything.  It's an indented key, so hope the formatting works here (hmm, not quite).

IDENTIFICATION KEY TO LOCALLY-GROWN GENERA OF CONIFERS AND RELATED GYMNOSPERMS

 

1. Leaves small, scale-like, hugging the stem in pairs or threes. 

  2.  Scale leaves with glandular dot in center; leafy stems more or less flattened, leaves on two sides flat and on two sides folded or keeled. 

3.  Leafy branches flattened into 2-dimensional sprays, leaf keel convexly rounded such that apex points inward toward stem; cones oblong...............................Arbor-vitae (Thuja)

3'. Leafy branches not flattened into sprays, or only slightly so, leaf keel straight or concavely curved such that apex points upward along stem axis; cones globose  ……………… ………………………….………………………….. White cedar (Chamaecyparis)

  2'. Scale leaves without glandular dots; leafy stems rounded or 4 sided.

 

               3.  Leaves in pairs or threes, vestigial, fused into papery sheath around green stems with widely spaced nodes...........................................................Mormon Tea (Ephedra)

 

                             3’. Scale leaves small, but not vestigial, some leaves may be needle-like in whorls of 3 around

                                                stem; nodes closely spaced………………………...Red Cedar, Juniper (Juniperus)

  1'. Leaves linear, long and narrow, or broad and flat, borne on stems singly, in clusters or whorls.

4. Leaves borne in bundles of 2s, 3s, or 5s, needle-like, stout to long and flexible,..........Pine (Pinus)

4’. Leaves borne in helical whorls on short side shoots and at the ends of twigs.

5.  Whorls of flat strap-like leaves (greater than 3 inches long) borne at ends of elongate shoots, each leaf subtended by a bract ……………………………………Japanese Umbrella Pine (Scaidopitys)

5’.  Whorls of leaves borne on short, stubby, lateral branches (spur shoots); broad leaves or needle leaves (3-sided or flat and less than 3 inches long). 

6. Leaves stiff, sharp, 3-sided; cones erect on branches, 2-3” long, evergreen; not hardy in our  region ...............................................................................Cedar (Cedrus)

6'. Leaves soft, flat needles or broad, flat, fan-shaped; deciduous.

7. Spur shoots  less than 5 mm diam., leaf scars tiny, hard to see; Leaves long, flat, linear, soft and flexible; cones persistent, pendant or surrounding branch, oval, 1-1.5”; tree branches more or less at right angles to trunk …………….......…Larch (Larix)

7'. Spur shoots greater than 5 mm diam., leaf scars >2 mm wide; leaves broad and fan-shaped, no cones; tree branches angle upwards ………………….Ginkgo (Ginkgo)

                4”.  Leaves borne individually along stems (spur shoots absent), sometimes arranged or arrayed in 2 ranks.

8. Leaves on side shoots arranged in 2 ranks producing  feather-like lateral shoots; leaves all soft and flexible; leafy shoots deciduous.

9.  Leaves usually less than 1 cm long; leafy shoots (or scars) alternate on main stem …………………...........................................................................Bald Cypress (Taxodium)

9’. Leaves mostly greater than 1.5 cm long; leafy shoots (or scars) opposite on main stem.............................. ……………………………………….Dawn Redwood (Metasequoia)

8'. Leaves mostly spirally arranged (sometimes reoriented to present flattened array of leaves); leaves thick, leathery or stiff and needle-like; leafy shoots evergreen.

                                                10. Leaves 4-sided needles, very stiff..............................................Spruce (Picea)

                                                10'. Leaves flattened (cannot roll between fingers), linear.

                                                                11. Leaves narrow abruptly to short discrete stalks; foliage not aromatic.

12. Leaves with 2 white bands on lower surface; needles on top of twigs upside down, pointing to twig apex; small seed cones (1 cm long) …. ....................... ………………………………....Hemlock (Tsuga)

12'. Leaves all green on both sides (lighter below), stems showing segments at base of leaf stalks; ovules terminal on short shoots, seeds  with red aril at maturity…………...............................................Yew (Taxus)

                                                                11'. Leaves not on short stalks, but taper narrowing to base; foliage aromatic

13. Leaves narrowing to an elliptical base, raised from twig at lower edge; buds dry, conical .................................................Douglas Fir (Pseudotsuga)

13'. Leaves narrowing to a flat, circular base; buds coated in resin, dome shaped …………………......................….....................Fir (Abies)

 

Field Guide to Gymnosperms & Book of Leaves

Nothing is better than well-illustrated plant books, except maybe an exceptional bottle of wine for under $10 (one can have dreams). Two newish books have come to the attention of the Phactor and both upon initial inspection seem quite good. The first is a field guide to Gymnosperms of the United State and Canada, and the wonderful illustrations may be glimpsted over at ArtPlantae, and do not let anyone anywhere try to tell you that photography can take the place of good botanical illustration. You'll love this book. However, as a field guide this book has not been tested to determine how well it works at actually identifying gymnosperms. Maybe some reader will have given it a go and let us know.
The second is a book about tree leaves, The Book of Leaves, more precisely the leaves of exactly 600 temperate zone trees. This is less of a field guide, being a rather hefty tome, and more of a reference book, but a quite handsome and very well done one. Each page has an excellent image of a leaf, full-sized (as much as the page allows) next to the full leaf, and an interesting commentary about the tree as well as its botanical specs. The tree selections, and you might quibble with a few, are selected from all the world's temperate zones, so yes, it includes Nothofagus as surely you were wondering. As a tropically oriented botanist, the temperate zone restriction is rather disappointing, but perhaps this will give the author, Allen Coombes, an idea for his next project. Looks like the Phactor has found a couple of presents to buy for that very special botanically-inclined someone. Or send this blog to someone as a hint of a present for yourself!