4. PEA FAMILY (Fabaceae)

BIG-LEAVED LUPINE Lupinus polyphyllus

GETTING A LIVING 

Many of us know about lupine, a common wildflower found in a variety of habitats, from reading "The Legend of Bluebonnet" to our children, a story about a young Comanche girl who sacrificed her favorite toy to save her tribe from starvation. Lupines are easily recognized as mostly large and shrubby plants with beautiful blue or purple spikes of pea-like flowers and distinct palmate shape leaves that look a bit like fingers emerging from the palm of a hand.  These fold up at night to minimize water and heat loss. Big-leaved lupine (Lupinus polyphyllus) favors montane and subalpine woodland edges as its prime habitat.

 DEFENSE 

Big-leaf lupine (L. polyphyllus) experiences reduced flower populations in early snowmelt year caused in part by frost damage to its flower buds. Early snowmelt is also correlated to a lengthening of a mid-season drought in June and early July that could reduce flower populations as well. In this instance, both frost and drought may paradoxically pose a threat as a consequence of climate warnings. Lupine alkaloids are poisonous for sheep, but not for birds, bear, elk, or rodents that feed on the plant's seed pods and roots. Alkaloids often defend against herbivores, but not so much for L. polyphyllus.

REPRODUCTION  

Pinch the keel of the lower flower part of most lupines, and out pops the stamens with  pollen squirting outward. Bees accomplish this same task with their buzzing and are on the receiving end of the  pollen shot that sticks to their belly and gets transported to the next flower. Once a flower is pollinated, its upper scoop-like banner turns from blue to white, telling the bee not to bother landing for nectar that's no longer available. An adaptation that eases the pollinator's task will  increase visits to other flowers on the same plant improving reproductive prospects.  Nature's bag of tricks focuses heavily on  competition and survival of the fittest, but also cooperative synergies .  

While different species compete for pollinators, multiple blooming species can support and attract more pollinators than otherwise. Pollinators experience reproductive benefits from overlapping blooms of different species that extend the total time in which flowers are blooming and supplying pollen. The reproductive lifespan of a pollinator can extend beyond the blooming period of any single plant species, and benefits from multiple sequential bloomers. This is the deal for L. polyphyllus (big-leaved lupine) and Lathyrus lanszwertii (peavine), given a normal linked blooming season. For these two species, the snowmelt date affects flowering overlap. In early snowmelt years, Lathyrus lanszwertii (peavine) moves its peak flowering date forward much more than L. polyphyllus (big-leaved lupine). The worry is that diminished co-flowering of such plants that share pollinators will have a negative impact on pollinator populations that could feed back on plant populations. If species flower separately in time, the gap between could lead to pollinator starvation and ultimately a reduction of  pollinator populations. This reduction in turn will mean less flower pollination and diminished plant reproduction.

PEAVINE (Lathyrus lanszwertii)

GETTING A LIVING  

Showing up normally in the same habitat with L. Pollyphylus in mid-June, Peavine (Lathyrus lanszwertii) possesses attractive classic pea-shaped creamy white flowers with bright pink nectar guides leading pollinators to their sweet reward and completion of the floral mating game. Lathyrus  occupies a variety of habitat types including sage-dominated dry meadows,  high-elevation subalpine meadows, and aspen woodlands.

DEFENSE. With snowmelt advancing steadily in subalpine mountain meadows,  Lathyrus is moving its dates of first and peak blooming ahead in time without any apparent loss in in its flower populations. It's ability to do so suggests that it is well defended against increase exposure to night frosts. For its co-flowering partner, Lupinus polyphyllus, as already noted, this is apparently not the case. As snowmelt advances, this species reduces the volume of its flower production and keeps its flowering peak out of the night frost time zone. A byproduct of this change is the decline of co-flowering by these two species as already explained.

REPRODUCTION 

Lathyrus shifted its blooming time forward with early snowmelt without apparently suffer substantially from night freezes, but it does face the danger of blooming prior to pollinators being very active or even emerging. Night frosts can slow bumblebee queen as well as solitary bee activity and reproduction and cause a delay in daily pollinating until the air has warmed sufficiently. Fewer pollinator visits can in turn result in reduced seed set and reproduction for  Lathyrus.  

Our two habitat-sharing pea species, big-leaved lupine and peavine, plants that play a key part in the beauty and diversity  of the high-mountain, subalpine summer wildflower bloom, give us hints about the complexity of climate change's likely effects on that plantlife that makes a special contribution to the wonders of our earthly existence. Climatic warming does more than simply cause droughts. It throws out of sync the timing (the phenology) of interacting species that depend on one another. Timing matters. Paradoxically, climatic warming also exposes plant life to increased threat from freezing temperatures.

3. THE BORAGE FAMILY (BORAGINACEAE)

DWARF BLUEBELLS (Mertensia fusiform) 

TALL BLUEBELLS (Mertensia ciliata)

GETTING A LIVING  

Dwarf bluebells (M. fusiformis) is among the earliest blooming wildflowers in the Rocky Mountain subalpine meadows near Crested Butte, Colorado, emerging and flowering just one or two weeks after snowmelt.  A plant of this species possesses thick leaves covered with stiff hairs that give it a measure of protection against frosty nights. The plant typically reaches peak blooming in early June, meaning that it emerges in May, a sometimes chilly month when nighttime freezes are common. The special advantage of early-blooming is an absence of competition from very many other species for resources and pollinators, more moisture, and less shading by other vegetation.  The danger of arriving early is damage to plant parts from night frosts and a scarcity of pollinating bumble bees whose own emergence and activity can be retarded by frosty nights. As emphasized in earlier posts, a warming climate induces early snowmelt and warmer early spring days, but leaves the timing of night frosts largely unchanged.

By the time M. fusiformis has gone to seed, it's late arriving tall bluebell (M. ciliata) cousin is in bloom, with its peak flowering occurring sometime in the first or second week of July. This species achieves a height of a meter or more with a single plant often covered with a lineup of multiple hanging flowers against a lush background of soft, hairless green leaves. It expands its coverage locally through clonal colonies created by networks of rhizomes, and favors wet meadows and stream-sides at subalpine and lower alpine elevations. 

DEFENSE

A changing climate affects both dwarf M. Fusiformis and tall M. Ciliate, moving peak blooming forward in time for both species as the date of spring snowmelt advances. The early blooming M. Fusiformis defends itself against night frosts with preformed underground ice-resistant flower buds and thick, ice resistant, hairy leaves, and avoids substantial losses of flower populations in years of early snowmelt and increased exposure to freezing night temperatures. Simply put, this species is pre-adapted to freezing from early blooming's normal increased exposure to frost. Its later blooming relation, M. Ciliata, does, however, suffer lower flower populations in early snowmelt years, but frost is unlikely to be the cause because it blooms so late in the summer. The problem for this species is likely to be a shortage of moisture caused by a lengthening and intensifying of the usual summer drought between snowmelt in May and the arrival of the summer monsoon rains in July and August. The earlier the snowmelt, the longer the drought.

REPRODUCTION 

Plants adapt to early season environmental variability in the form of frost damage or shortage of pollinators by producing flowers that develop later or last longer if un-pollinated giving them a shot at delayed pollination. Some also develop a capacity for early self-pollination, but this is not the case for outcrossing M. Fusiformis. For early blooming M. Fusiformis, a late snow melt in 2008 led to a short but intense and productive flowering period. An early snow melt in 2007 caused a longer flowering season and more late opening flowers. The total number of flowers didn't differ between years but the flowering peak shifted forward in 2007 and early arriving flowers did get exposed to some frost damage. Extended longevity of unpollinated flowers and the production of numerous late season flowers may be giving this species some resilience against climatic warming and the damage of early snowmelt. Possibly because of plant damage from hard frosts, seed set was nonetheless lower in 2007 than 2008.  

As already noted, climate change and early snow melt causes peak blooming to jump farther forward for M. Fusiform than it does for its later blooming taller relation, M. Ciliata. This growing gap could leave bumble bees in a lurch without a source of nectar and pollen in some localities, potentially diminishing their populations. This could in turn create a pollinator shortage for the late blooming M. Ciliata and eventually cause its population to decline. Fortunately, so far researchers don't find any evidence of an actual pollinator shortage. Whatever the cause, in early snowmelt years, the total number of flowers for late blooming M. Ciliata  drops substantially, and some locations plant populations disappear completely where they have been observed in the past. The most likely culprit is a lengthened and intensified midsummer drought caused by earlier snow melts.

To sum up, so far the early-blooming M. Fusiformis has stood up to the challenge of climatic warming, probably because of its pre-adaptation to the night frost problem, but late-blooming  M. Ciliata populations and reproduction appear to be suffering from midsummer moisture shortages occurring because of a warming climate.