After the early
spring ephemerals have bloomed Jack in the Pulpit emerges, typically in moist
situations. In the SBG they can be found alongside the trail
that leads from
the formal garden to the bridge over the creek that runs beside the Orange trail . This unusual plant is in the Arum
family (Araceae; pronounced: ah-Ray-see-e).
All the Arums have the same reproductive structure: a central column,
called a spadix, that bears flowers and is partially or completely surrounded
by a spathe. In Jack in the Pulpit the spathe forms the "pulpit" and the
"preacher" inside is the "Jack." But it's a little sexist
to call every such plant Jack-in-the-Pulpit because the sexes occur in separate
plants. A spadix usually bears either all male flowers or all female flowers.
So some of the "jacks" are really "jills."
 | ||
| Jack peeking out over the pulpit edge |
Telling males from females
How do you
tell them apart? There are two ways. The jills are larger plants with two
leaves, while the jacks have only a single leaf. (What looks like three leaves
is really a single leaf with three leaflets.) So if all the pulpits are growing
from single leaved plants they are truly jacks, i.e., male.
The second
way to sex a Jack-in-the-Pulpit is to carefully open the spathe. By gently
pulling apart the overlapping edges of the spathe you can see the flowers on
the lower part of the spadix. These flowers have no petals or sepals. If they
are plump and green with white centers you are looking at a jill. The jack
spadix has numerous small, non-plump flowers with dark anthers and pink pollen.
Deciding to be jack or jill.
Jack in the
Pulpit is a perennial plant, so you might think that a single plant would
remain the same sex from year to year. But nature is full of surprises. Jack
in the Pulpit can change sex from one year to the next. Whether it develops as
a male or female apparently depends on how much food it has stored during the
previous years growth. If there is sufficient food stored in the corm then a
female will emerge the following spring. If not, then the plant will develop as
a male, or may not even produce an inflorescence if its stored energy is too little. Now you can understand the reason
for the two leaves in female plants. After pollen has been delivered to the
ovules the plant must have enough energy to develop its seeds, a process that
takes all summer. Having two leaves increases the amount of sunlight captured
to feed the growing seeds. Typically, if a plant has assumed the female role in
one year, then the energy consumed in producing seeds will be so large that the
plant reverts to being male in the next year.
You can find more details about the interesting life history of Jack-in-the-Pulpit in the book by Carol Gracie: Spring Wildflowers of the Northeast: A Natural History, 2012, Princeton University Press.
