Monocot or Dicot?

A self-examination

It is said that the Monocot-Dicot differences are predictive and obvious.  The following self test ought to reveal some of the difficulties with how these definitions work.


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This is a close-up of the stamens of a Monocot.  The genus name is Amaryllis, and the family name is the Amaryllidaceae.   You can count six stamens, and below out of focus is a stigma of three parts.

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This is a dicot.  The five stamens are obvious.  Also note the five-parted corolla.  The corolla is sympetaous.  The plant shown here is Solanum caroliense, the horse nettle.  It is a common summer "weed" in open fields.  It is in the Solanceae, which is the family potato is in.  This flower closely resembles the flower of a potato.

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So, how do you know what class this belongs to?  Can you count the stamens?  Can you count the petals?  In this instance you will need to see how many petals are there, and if that is not good enough, check the leaves for netted or parallel venation.  This is a dicot.  It is a california poppy, a popular ornamental in our area.

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This is bloodroot, Sanguinaria canadensis, a dicot.  Neither the male parts or the petals shown here show a predictable number based on 3, 6 or five.  In this instance, it is going to be the leaves that tell you if this is a monocot or dicot.  Check the leaf to the right.

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This is a monocot.  From this picture you cannot tell that.  It is in the Poaceae, the grass family, which is a monocot family.  The flower parts are not easy to identify unless you have a hand lens, but when you check out the leaves, they will have parallel veins.  This same is true for the sedge (Cyperaceae), to the right, but you can make out a three-lobed stigma.

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The flower parts show you it is clearly a monocot, but look at the leaves.   They are not all that parallel veined. Trilliums are known for their variation, and when this occurs, it can be confusing.

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There are six petals.  It is a monocot?  Wrong.  The leaves tell you it is a dicot.  This is a Clematis, and it belongs to the buttercup family, (Ranunculaceae) which notoriously has petal numbers that never always remain within the dicot definition.

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Here you go again:  six petals.  I have seen buttercups with five or six petals.  This is Ranunculus bulbosus, another example of variation in petal number in the Ranunculaceae.  The leaves will show netted venation.  This is a dicot.

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There are spurred petals.  Count them.  There are five.  This is a dicot, and the netted venation of the leaves will bear this out.  The plant is a colombine, Aquilegia canadensis, and the number of spur this time is always five.  

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Although these petals are a bit difficult to number, you will see six of them.  This is the flower of a floating aquatic called water hyacinth.

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This is the leaf of Dioscorea quaternata, the wild yam.  The leaves are parallel veined, although you can see some net-like connections between the veins.  It is a monocot.

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Orchids have very exotically shaped flowers.  Very often it is difficult to find the actual 3 petals.  The leaves will always be parallel veined.  It will be a monocot.  This is Orchis spectabilis, the showy orchis.

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In this example. the flowers are microscope.  The cattail inflorescence is memorable.  It is a monocot because of the parallel veined leaves that are sword-like (linear-lancolate).

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This is a monocot.  The flower is Commelina, the dayflower.  You can see the three petals, although one of them is not as colored as the other two.  The leaves will have parallel veins.

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The parallel veins of the leaves will give this one away.  There are six stamens, and three petals.  It is a monocot.  This is Tradescantia, the spider plant.  
monocotdicot7.jpg (30774 bytes) Here is the classic way that many monocot leaves are organized:  linear-lanceolate clasping leaves that are alternate in arrangement.  The leaves are parallel veined.  This is a monocot called Zebrina, the wandering jew.
monocotdicot8.jpg (28037 bytes) The main veins of this arrowhead are parallel, but a closer look reveals the veins to be connected.  It is a monocot if you saw the flowers. The arrowhead, Saggitaria (Alismataceae), is a common aquatic plant.  This picture was taken at Wildwood Park.
monocotdicot9.jpg (36924 bytes) This is a monocot.  The parallel veins are obvious, and you can see that the flowers are very small.  This is Smilacina racemosa, the false Solomon's seal (Liliaceae).

Biology 207 students may click  here  for a continuation of the Monocot-Dicot study